The startup I co-founded (Adioso - YC W09 [1]) tried to do it, including having discussions with a travel insurance provider about offering "layover protection" - so that if one leg was delayed causing you to miss your onward leg(s), your costs are covered. Kiwi.com does this now.
We worked on it from about 2008 till 2013 then basically gave up, as it was too hard to offer a service that customers could really love and trust. (It wasn't for nought; the technology we developed was valuable, and the company was able to rebrand and pivot and now does important work for airlines to optimise loads and fares [2], though I left when the rebrand/pivot happened).
The thing that makes it hard to do is it's basically impossible to get all the flight inventory, including fares and seat availability, that's complete and up-to-date enough to deliver a service that customers can trust.
The engineering challenge is one thing - solving a multi-dimensional travelling salesman problem (price and distance/duration) highly repetitively - but you can solve that with enough smart engineers and "compute", which ITA did in the early 2000s, and on a smaller scale, our team did a decade later.
But you could build the most beautiful routing engine the universe has ever seen, and still have a user experience that's kind-of garbage because the industry just keeps the flight inventory data so locked down.
These days there are APIs and feeds available from the major distribution platforms - Sabre, Amadeus and Travelport, but it's still not comprehensive. You often still need to negotiate individual agreements with major airlines in order to be able to publish and sell their fares. And even then, many of the low-cost airlines (which are often most of interest to travellers who want to find the cheapest route and deal with self-transfer) are not available through these distributors, and some, like South West, have blanket refused to be on 3rd party search sites, only starting to relax that position very recently and only with the dominant platform [3]. Kiwi.com has only recently come to a partnership agreement with RyanAir [4] after being in legal battle with them for years [5]. (I hate the thought of having to be at war with your most important partners).
Others have mentioned Skyscanner, which was always the closest to us in what we were each trying to offer (we talked briefly with them about being acquired by them).
Right from the beginning when we got funded for Adioso, my mind became fixated on the thought "if only you get every single flight in the world loaded into one big graph database, what could you do with it?", but it turned out to be a very big "if".
Why would airlines even want penny pinching customers to snag the best deals via a third party?
At the very least it would make more sense to let their own frequent flyers snag such deals.
Same reason they offer deals in the first place, price discrimination and yield management.
One reason I could see is to keep perceived price level for the frequent flyers. If they don't see best deals they won't expect those. And the hardcore deal hunters are not loyal to you or your brand.
Giving frequent flyers very good deals make them expect them, thus not be so willing to pay "regular" price.
To fill empty seats ? Still better than nothing
I've never understood the comments on all of the posts like this advising people to never book via a third party. Is it an American thing?
I've probably been on around 250 flights in the past 7 years in Europe and I can't remember one time that it was cheaper to book directly than through some third party. Sometimes it's the same price to book direct, but it doesn't matter either way: the support you're going to get is the same, and the insurance or whatever depends on... exactly whatever you've paid for already.
I still have fond memories of their legendary (pre-leetcode) coding challenges [0] posted on the T (they also hosted the Boston Lisp users group in the early 2000s which was filled with mind-blowingly incredibly brilliant people, everyone there seemed to be an expert in software and had a PhD in some other, non-related field)
Having worked a bit in the travel industry, I highly recommend that you never book through a third party (by all means use their search). Third party apps are not allowed by airlines to charge less than the airline and typically have abysmal customer service, and I can assure you any "add-ons" offered by a third party are ultimately a scam.
> Third party apps are not allowed by airlines to charge less than the airline
How come I regularly see third-party OTAs offer the same itineraries cheaper than the airline then?
Sometimes there's a mystery fee added just before payment, but not nearly always – and I've flown such itineraries once or twice myself (if the difference was significant and I was absolutely certain I wouldn't need any change or extra service).
I was under the impression that these effectively share part of their agent fee with the traveler as a form of kickback (to appear as the cheapest option in search, which in the end might end up a win-win for both).
One trick they use is to book via a different country. Flight from A to B when booked on the main English website in dollars can be a higher price than the same leg being booked on the Russian website in rubles.
Two reasons for that, one can be because the airline is less known in that market and whats to price more aggressively, and the other is that the ticket conditions are slightly different. For example your right to get compensation in case of a delay (and how much) may be different between those tickets.
One way I've heard is they don't book your ticket immediately but predict when the airline's price will go down and book in then. I imagine they have far better data to enable price prediction than the general public, and can spread the cost of getting it wrong over their other customers.
At least the ones I’ve used have always sent me a ticket number within at most a few hours, and usually instantly. I’d be surprised if that really was a factor these days.
From what I remember from working in the industry many years ago, the process is actually split into (at least) 3 parts.
1. Reservation
2. Booking
3. Ticketing
Each step has its own expiration dates set by the airline, which can range from "instant" to several days/weeks. They may also set different cancelation fees for each step. A smart travel agent could in theory use this to cancel an old booking and book again if the price is reduced, but I think some airlines have changed their practice to avoid this.
Keep in mind that I mostly worked for the European market. I know US airlines operate a bit differently from the rest of the world. They usually have more flexible rules around flights and exchanging of tickets.
> Third party apps are not allowed by airlines to charge less than the airline
Technically true in that they can't undercut the airline on the same fare class.
But there are many different fare classes and some of them are only offered via 3rd parties, so you can often get much better deals via e.g., Expedia than you can by going direct to the airline.
Just this year my family flew Melbourne-Madrid then Milan-Melbourne, both legs on Cathay, but this route was only available on Expedia (and maybe other OTAs too, I don't remember) - all I know was that it was impossible to even search for this route on Cathay's own website. We didn't have any issues, but if we did I don't know if I'd worry about Expedia's customer service being much worse than an airline's own service.
> We didn't have any issues, but if we did I don't know if I'd worry about Expedia's customer service being much worse than an airline's own service.
The problem (speaking as someone who has to deal with Travel Agents many, many times) is that Expedia will say it's Cathay's problem, and Cathay will refuse to speak to you and tell you it's Expedia's problem.
Airlines own systems are often awful UI and in case of some asian low costers your data is immediately sold to spammers (and they collect as much your data as they can too).
Depends on exact case but if traveling on a budget going with low costers and connections a good third party can be better than an unknown shitty airline's system.
I used Expedia a few years back, got a lower price and could cancel for full refund within a day but they probably don't do that anymore. Kiwi seemed okay. Ctrip now owned by China.
I'd be very careful with Kiwi. They don't have official OTA agreements with all the airlines they resell; at least Ryanair at one point was actively hostile towards them, and Kiwi was working with personal Ryanair accounts to get around their roadblocks. This in turn meant I couldn't access Ryanair's mobile boarding passes and had to find a printer on short notice at the airport.
While airlines can apparently not legally completely prevent such "uncooperative" third-party resellers, and I do have some sympathy for the business model, it's not great to be stuck between travel agent and airline when things go wrong.
Other OTAs like Experian actually take the role of a good old travel agent (the entity historically doing much of the ticketing work the airlines are now doing directly) and will usually only sell you itineraries of interlining (i.e. cooperating) airlines, and also only of airlines that accept travel agents as business partners in the first place.
I have bad experiences with Kiwi and ctrip and a bunch of other ones. The support is indeed terrible and if anything goes wrong, the airline will tell you to contact the 3rd party agent... which has horrible support so there you are, stuck somewhere in asia. I had multiple occasions in which I just booked another ticket because of their incompetence, losing a few $100 as I could not take the risk of being late. Now I only book directly at the airline: at that time the company was booking and they just took what google flights gave them, which is often not directly at the airline.
Expedia still offers refunds within 24 hours. At least for every flight I've booked originating from the US in the last few years.
I thought it was because of the DoT rule, but apparently they wouldn't be subject to that.
[deleted]
One search feature I wanted was a way to look up a list of all flights leaving an airport on a certain day.
In the early stages of vacation planning, it’s be fun to see a list of all possible direct flights to evaluate my options, but the use case of doing flight searches with an unknown destination isn’t too common. Basically, i want to be able to browse flights like a bus schedule and just see what the possibilities are from a particular start point
Not exactly what you want, but https://www.flightconnections.com is nice to learn "where I can fly from airport X in 1 hop / 2 hops".
You could use flightaware.com for this. Just search a date and a departure airport. The caveat is that the list will be fairly large, with a lot of repeats.
You can get something similar from https://www.kayak.com/explore/ except the results are shown on a map rather than as a list: you specify an origin (and optionally a departure date) and the map shows price icons at all possible destinations.
> One search feature I wanted was a way to look up a list of all flights leaving an airport on a certain day.
Skyscanner does this pretty well.
Google Flights does this really well - just leave the destination empty or use something generic, like Europe/USA. I do this all the time to find new places to go to.
The leading response does a good job calling out that this is pretty risky for the traveller. Similar to skip lagging, if anything goes wrong you can end up is a pretty difficult position.
Even if you have insurance that can cover the cost of the low cost connection ticket you just missed.. try buying a new ticket at the airport for that same day or same week even and you’ve now spent more than getting a regular ticket in the first place. And that regular ticket airline is responsible for getting you to your final destination.
I did some extreme budget flying as a youth and you might just get stranded at a random airport so you better be very flexible with your plans. If it’s inside the US maybe you’re fine to rent a car or take a bus or something but if you happened to layover in UAE or something then it gets trickier
One use case I’d love to see is the ability to find the best price for multiple city tickets.
I’m fairly flexible on dates, but getting the best price for it is a super iterative process. Having some similar functionality like excel’s solve function would be awesome to find optimal dates within a range for each destination.
kiwi.com is also pretty good at this.
I worked on this for tripstack a while ago. They offer it through their partners. Kiwi is the other one who made it a thing. Now it’s more common to see it all over.
I think Google Flights can do that?
They can; this usually shows up with a remark of "separate tickets".
There are considerable caveats when doing that – it's generally not advisable for connecting flights (you're essentially on the hook for missed connections etc.), and even just for separate outbound and return tickets it can mean trouble (e.g. if the outbound flight is cancelled, there is no obligation for the separate ticket to be refunded to you).
Granted I only travel with hand luggage, I never had any issues with cancelled or delayed flighs when booking separate tickets. Even so they are relatvely cheap. It is even cheaper if you book your return flight ticket separately.
You need to be more clear about what you meant by saying "never had issues".
The point is there might be issues because the second flight has no obligation to refund you if you're late (but they might still do out of generosity).
It's not like it's gonna happen all the time. So having data points saying that didn't happen is kinda pointless.
> Granted I only travel with hand luggage
That makes an enormous difference, since you usually can do your check-in online a day or more before departure.
I just had a flight where I had purchased my connections on separate tickets. When I arrived at the baggage drop-off, it was closed and no staff from the airline was anywhere. So I had to bring my big suitcase along through security and then the airline staff at the gate was friendly enough to check it in for me for free.
But if you're bringing anything in your checked luggage that security doesn't like, you will have to just leave that item at the airport. You might also have to pay a high fee to bring it to the gate instead of checking it, depending on airline. I had purchased my ticket directly from the airline, so maybe they treated me better because of it?
Skyscanner
Isn't that what Expedia does?
As explained in the answer, almost always Expedia will issue a single ticket across one or more airlines (the technical term for that is "interlining"), which is different from an itinerary made up of actually separately issued tickets.
In the former case, there's always exactly one airline responsible for getting you to your destination in case of a missed connection or itinerary changes; in the latter case, you're often on your own.
I used Kiwi.com for this a few weeks ago (combining multiple European carriers, including Ryanair) and it worked rather well.
My first flight was delayed, and it seemed likely I would miss the second leg flight, so they sent me an email with a list of options to reschedule. I'd purchased the 'Premium Protection', so I think I could choose a new option up to €250 (+ hotel if overnight) without paying any extra.
I decided to risk taking the first flight, as the second airport was much bigger so figured there would be better flights from there. Fortunately the flight on the second leg was delayed too, so I didn't need to change anything.
What Kiwi.com is doing with their "separate tickets plus connection insurance" model is called "virtual interlining", and it's an interesting alternative in some scenarios (well-connected airports with many alternatives). But I'd still never risk it on an important connection.
I've had a very bad experience with Kiwi.com myself: I booked a Ryanair flight on them without realizing that Ryanair is actively trying to prevent Kiwi from reselling their flights. Kiwi.com apparently works around this by booking tickets on pools of Ryanair retail accounts, to which they don't share the credentials with travelers – making mobile check-in impossible. (And Ryanair at least at the time was charging over 100€ of a "service fee" for a boarding pass print at the airport...)
This is only marginally related to booking separate tickets, but I suppose the larger point is that it's never a great situation to be stuck between the lines of two companies actively hostile towards each other, when you really depend on their cooperation to get to your destination.
"Official" interline agreements are an explicit statement that two or more airlines will make at least some reasonable effort to get you and your luggage to your destination, and will be on the hook for it (under ICAO regulations) if things don't work out.
skiplagged shows you “self-transfer” flight options, which i think solves what OOP was asking
[flagged]
What kind of sexist drivel is this?
[dead]
A web search engine that combines results from different web sites? (2022) (openai.com)
It's called "virtual interlining".
The startup I co-founded (Adioso - YC W09 [1]) tried to do it, including having discussions with a travel insurance provider about offering "layover protection" - so that if one leg was delayed causing you to miss your onward leg(s), your costs are covered. Kiwi.com does this now.
We worked on it from about 2008 till 2013 then basically gave up, as it was too hard to offer a service that customers could really love and trust. (It wasn't for nought; the technology we developed was valuable, and the company was able to rebrand and pivot and now does important work for airlines to optimise loads and fares [2], though I left when the rebrand/pivot happened).
The thing that makes it hard to do is it's basically impossible to get all the flight inventory, including fares and seat availability, that's complete and up-to-date enough to deliver a service that customers can trust.
The engineering challenge is one thing - solving a multi-dimensional travelling salesman problem (price and distance/duration) highly repetitively - but you can solve that with enough smart engineers and "compute", which ITA did in the early 2000s, and on a smaller scale, our team did a decade later.
But you could build the most beautiful routing engine the universe has ever seen, and still have a user experience that's kind-of garbage because the industry just keeps the flight inventory data so locked down.
These days there are APIs and feeds available from the major distribution platforms - Sabre, Amadeus and Travelport, but it's still not comprehensive. You often still need to negotiate individual agreements with major airlines in order to be able to publish and sell their fares. And even then, many of the low-cost airlines (which are often most of interest to travellers who want to find the cheapest route and deal with self-transfer) are not available through these distributors, and some, like South West, have blanket refused to be on 3rd party search sites, only starting to relax that position very recently and only with the dominant platform [3]. Kiwi.com has only recently come to a partnership agreement with RyanAir [4] after being in legal battle with them for years [5]. (I hate the thought of having to be at war with your most important partners).
Others have mentioned Skyscanner, which was always the closest to us in what we were each trying to offer (we talked briefly with them about being acquired by them).
Right from the beginning when we got funded for Adioso, my mind became fixated on the thought "if only you get every single flight in the world loaded into one big graph database, what could you do with it?", but it turned out to be a very big "if".
[1] https://techcrunch.com/2010/08/31/adioso/
[2] https://amadeus.com/en/blog/articles/creating-a-private-resa...
[3] https://techcrunch.com/2010/08/31/adioso/
[4] https://media.kiwi.com/company-news/kiwi-com-and-ryanair-ann...
[5] https://www.travolution.com/news/kiwi.com-celebrates-three-w...
Why would airlines even want penny pinching customers to snag the best deals via a third party?
At the very least it would make more sense to let their own frequent flyers snag such deals.
Same reason they offer deals in the first place, price discrimination and yield management.
One reason I could see is to keep perceived price level for the frequent flyers. If they don't see best deals they won't expect those. And the hardcore deal hunters are not loyal to you or your brand.
Giving frequent flyers very good deals make them expect them, thus not be so willing to pay "regular" price.
To fill empty seats ? Still better than nothing
I've never understood the comments on all of the posts like this advising people to never book via a third party. Is it an American thing?
I've probably been on around 250 flights in the past 7 years in Europe and I can't remember one time that it was cheaper to book directly than through some third party. Sometimes it's the same price to book direct, but it doesn't matter either way: the support you're going to get is the same, and the insurance or whatever depends on... exactly whatever you've paid for already.
Happy to see ITA software mentioned in the comments: https://matrix.itasoftware.com/search
I still have fond memories of their legendary (pre-leetcode) coding challenges [0] posted on the T (they also hosted the Boston Lisp users group in the early 2000s which was filled with mind-blowingly incredibly brilliant people, everyone there seemed to be an expert in software and had a PhD in some other, non-related field)
Having worked a bit in the travel industry, I highly recommend that you never book through a third party (by all means use their search). Third party apps are not allowed by airlines to charge less than the airline and typically have abysmal customer service, and I can assure you any "add-ons" offered by a third party are ultimately a scam.
0. https://github.com/mattbraz/ita-puzzles
> Third party apps are not allowed by airlines to charge less than the airline
How come I regularly see third-party OTAs offer the same itineraries cheaper than the airline then?
Sometimes there's a mystery fee added just before payment, but not nearly always – and I've flown such itineraries once or twice myself (if the difference was significant and I was absolutely certain I wouldn't need any change or extra service).
I was under the impression that these effectively share part of their agent fee with the traveler as a form of kickback (to appear as the cheapest option in search, which in the end might end up a win-win for both).
One trick they use is to book via a different country. Flight from A to B when booked on the main English website in dollars can be a higher price than the same leg being booked on the Russian website in rubles.
Two reasons for that, one can be because the airline is less known in that market and whats to price more aggressively, and the other is that the ticket conditions are slightly different. For example your right to get compensation in case of a delay (and how much) may be different between those tickets.
One way I've heard is they don't book your ticket immediately but predict when the airline's price will go down and book in then. I imagine they have far better data to enable price prediction than the general public, and can spread the cost of getting it wrong over their other customers.
At least the ones I’ve used have always sent me a ticket number within at most a few hours, and usually instantly. I’d be surprised if that really was a factor these days.
From what I remember from working in the industry many years ago, the process is actually split into (at least) 3 parts.
1. Reservation
2. Booking
3. Ticketing
Each step has its own expiration dates set by the airline, which can range from "instant" to several days/weeks. They may also set different cancelation fees for each step. A smart travel agent could in theory use this to cancel an old booking and book again if the price is reduced, but I think some airlines have changed their practice to avoid this.
Keep in mind that I mostly worked for the European market. I know US airlines operate a bit differently from the rest of the world. They usually have more flexible rules around flights and exchanging of tickets.
> Third party apps are not allowed by airlines to charge less than the airline
Technically true in that they can't undercut the airline on the same fare class.
But there are many different fare classes and some of them are only offered via 3rd parties, so you can often get much better deals via e.g., Expedia than you can by going direct to the airline.
Just this year my family flew Melbourne-Madrid then Milan-Melbourne, both legs on Cathay, but this route was only available on Expedia (and maybe other OTAs too, I don't remember) - all I know was that it was impossible to even search for this route on Cathay's own website. We didn't have any issues, but if we did I don't know if I'd worry about Expedia's customer service being much worse than an airline's own service.
> We didn't have any issues, but if we did I don't know if I'd worry about Expedia's customer service being much worse than an airline's own service.
The problem (speaking as someone who has to deal with Travel Agents many, many times) is that Expedia will say it's Cathay's problem, and Cathay will refuse to speak to you and tell you it's Expedia's problem.
Airlines own systems are often awful UI and in case of some asian low costers your data is immediately sold to spammers (and they collect as much your data as they can too).
Depends on exact case but if traveling on a budget going with low costers and connections a good third party can be better than an unknown shitty airline's system.
I used Expedia a few years back, got a lower price and could cancel for full refund within a day but they probably don't do that anymore. Kiwi seemed okay. Ctrip now owned by China.
I'd be very careful with Kiwi. They don't have official OTA agreements with all the airlines they resell; at least Ryanair at one point was actively hostile towards them, and Kiwi was working with personal Ryanair accounts to get around their roadblocks. This in turn meant I couldn't access Ryanair's mobile boarding passes and had to find a printer on short notice at the airport.
While airlines can apparently not legally completely prevent such "uncooperative" third-party resellers, and I do have some sympathy for the business model, it's not great to be stuck between travel agent and airline when things go wrong.
Other OTAs like Experian actually take the role of a good old travel agent (the entity historically doing much of the ticketing work the airlines are now doing directly) and will usually only sell you itineraries of interlining (i.e. cooperating) airlines, and also only of airlines that accept travel agents as business partners in the first place.
I have bad experiences with Kiwi and ctrip and a bunch of other ones. The support is indeed terrible and if anything goes wrong, the airline will tell you to contact the 3rd party agent... which has horrible support so there you are, stuck somewhere in asia. I had multiple occasions in which I just booked another ticket because of their incompetence, losing a few $100 as I could not take the risk of being late. Now I only book directly at the airline: at that time the company was booking and they just took what google flights gave them, which is often not directly at the airline.
Expedia still offers refunds within 24 hours. At least for every flight I've booked originating from the US in the last few years.
I thought it was because of the DoT rule, but apparently they wouldn't be subject to that.
One search feature I wanted was a way to look up a list of all flights leaving an airport on a certain day.
In the early stages of vacation planning, it’s be fun to see a list of all possible direct flights to evaluate my options, but the use case of doing flight searches with an unknown destination isn’t too common. Basically, i want to be able to browse flights like a bus schedule and just see what the possibilities are from a particular start point
Not exactly what you want, but https://www.flightconnections.com is nice to learn "where I can fly from airport X in 1 hop / 2 hops".
You could use flightaware.com for this. Just search a date and a departure airport. The caveat is that the list will be fairly large, with a lot of repeats.
You can get something similar from https://www.kayak.com/explore/ except the results are shown on a map rather than as a list: you specify an origin (and optionally a departure date) and the map shows price icons at all possible destinations.
> One search feature I wanted was a way to look up a list of all flights leaving an airport on a certain day.
Skyscanner does this pretty well.
Google Flights does this really well - just leave the destination empty or use something generic, like Europe/USA. I do this all the time to find new places to go to.
The leading response does a good job calling out that this is pretty risky for the traveller. Similar to skip lagging, if anything goes wrong you can end up is a pretty difficult position.
Even if you have insurance that can cover the cost of the low cost connection ticket you just missed.. try buying a new ticket at the airport for that same day or same week even and you’ve now spent more than getting a regular ticket in the first place. And that regular ticket airline is responsible for getting you to your final destination.
I did some extreme budget flying as a youth and you might just get stranded at a random airport so you better be very flexible with your plans. If it’s inside the US maybe you’re fine to rent a car or take a bus or something but if you happened to layover in UAE or something then it gets trickier
One use case I’d love to see is the ability to find the best price for multiple city tickets.
I’m fairly flexible on dates, but getting the best price for it is a super iterative process. Having some similar functionality like excel’s solve function would be awesome to find optimal dates within a range for each destination.
kiwi.com is also pretty good at this.
I worked on this for tripstack a while ago. They offer it through their partners. Kiwi is the other one who made it a thing. Now it’s more common to see it all over.
I think Google Flights can do that?
They can; this usually shows up with a remark of "separate tickets".
There are considerable caveats when doing that – it's generally not advisable for connecting flights (you're essentially on the hook for missed connections etc.), and even just for separate outbound and return tickets it can mean trouble (e.g. if the outbound flight is cancelled, there is no obligation for the separate ticket to be refunded to you).
Granted I only travel with hand luggage, I never had any issues with cancelled or delayed flighs when booking separate tickets. Even so they are relatvely cheap. It is even cheaper if you book your return flight ticket separately.
You need to be more clear about what you meant by saying "never had issues".
The point is there might be issues because the second flight has no obligation to refund you if you're late (but they might still do out of generosity).
It's not like it's gonna happen all the time. So having data points saying that didn't happen is kinda pointless.
> Granted I only travel with hand luggage
That makes an enormous difference, since you usually can do your check-in online a day or more before departure.
I just had a flight where I had purchased my connections on separate tickets. When I arrived at the baggage drop-off, it was closed and no staff from the airline was anywhere. So I had to bring my big suitcase along through security and then the airline staff at the gate was friendly enough to check it in for me for free.
But if you're bringing anything in your checked luggage that security doesn't like, you will have to just leave that item at the airport. You might also have to pay a high fee to bring it to the gate instead of checking it, depending on airline. I had purchased my ticket directly from the airline, so maybe they treated me better because of it?
Skyscanner
Isn't that what Expedia does?
As explained in the answer, almost always Expedia will issue a single ticket across one or more airlines (the technical term for that is "interlining"), which is different from an itinerary made up of actually separately issued tickets.
In the former case, there's always exactly one airline responsible for getting you to your destination in case of a missed connection or itinerary changes; in the latter case, you're often on your own.
I used Kiwi.com for this a few weeks ago (combining multiple European carriers, including Ryanair) and it worked rather well.
My first flight was delayed, and it seemed likely I would miss the second leg flight, so they sent me an email with a list of options to reschedule. I'd purchased the 'Premium Protection', so I think I could choose a new option up to €250 (+ hotel if overnight) without paying any extra.
I decided to risk taking the first flight, as the second airport was much bigger so figured there would be better flights from there. Fortunately the flight on the second leg was delayed too, so I didn't need to change anything.
What Kiwi.com is doing with their "separate tickets plus connection insurance" model is called "virtual interlining", and it's an interesting alternative in some scenarios (well-connected airports with many alternatives). But I'd still never risk it on an important connection.
I've had a very bad experience with Kiwi.com myself: I booked a Ryanair flight on them without realizing that Ryanair is actively trying to prevent Kiwi from reselling their flights. Kiwi.com apparently works around this by booking tickets on pools of Ryanair retail accounts, to which they don't share the credentials with travelers – making mobile check-in impossible. (And Ryanair at least at the time was charging over 100€ of a "service fee" for a boarding pass print at the airport...)
This is only marginally related to booking separate tickets, but I suppose the larger point is that it's never a great situation to be stuck between the lines of two companies actively hostile towards each other, when you really depend on their cooperation to get to your destination.
"Official" interline agreements are an explicit statement that two or more airlines will make at least some reasonable effort to get you and your luggage to your destination, and will be on the hook for it (under ICAO regulations) if things don't work out.
skiplagged shows you “self-transfer” flight options, which i think solves what OOP was asking
[flagged]
What kind of sexist drivel is this?
[dead]
A web search engine that combines results from different web sites? (2022) (openai.com)
Kayak.com might be what you are looking for.