# Duffel Flights and Stays API vs Kiwi.com MCP Server

> Duffel Flights and Stays API scores 66.7 (B) on agent readiness against Kiwi.com MCP Server's 51.9 (D), and leads in 6 of 7 scored categories. Kiwi.com MCP Server leads on payments & pricing. Both do travel flights. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/duffel-vs-kiwi-mcp
- Markdown: https://www.anchorterminal.com/compare/duffel-vs-kiwi-mcp.md (~2,400 tokens)
- Slim: https://www.anchorterminal.com/compare/duffel-vs-kiwi-mcp.min.md (~730 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/duffel-vs-kiwi-mcp.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-08

Duffel Flights and Stays API scores 66.7 (B) on agent readiness against Kiwi.com MCP Server's 51.9 (D), and leads in 6 of 7 scored categories. Kiwi.com MCP Server leads on payments & pricing. Both do travel flights.

- Duffel Flights and Stays API: grade B, 66.7/100, rank #230 of 722. Markdown https://www.anchorterminal.com/tools/duffel.md · JSON https://www.anchorterminal.com/api/v1/tools/duffel.json
- Kiwi.com MCP Server: grade D, 51.9/100, rank #571 of 722. Markdown https://www.anchorterminal.com/tools/kiwi-mcp.md · JSON https://www.anchorterminal.com/api/v1/tools/kiwi-mcp.json

## Which one, for what

### Duffel Flights and Stays API (B)

Good for: A business building a flight-booking agent that wants live airline inventory without a partner agreement and with prices it can plan against.

Ahead on:
- Reliability, 70 against 45
- Agent ergonomics, 80 against 66
- Security & auth, 60 against 54
- Maintenance & community, 92 against 13
- Transparency & trust, 75 against 66

Watch for: No OpenAPI document, llms.txt or official MCP server

### Kiwi.com MCP Server (D)

Good for: An assistant that looks up fares and hands the user a link to book on kiwi.com, with no setup.

Ahead on:
- Payments & pricing, 55 against 40

Also in its favour:
- No key needed to call it

Watch for: Search only. Booking, payment, changes and cancellations happen on kiwi.com through the `bookingUrl` in each result


## Score by category

| Category | Weight | Duffel Flights and Stays API | Kiwi.com MCP Server | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 70 | 45 | Duffel Flights and Stays API +25 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 59 | 55 | Duffel Flights and Stays API +4 |
| Agent ergonomics | 13% (16.2 this run) | 80 | 66 | Duffel Flights and Stays API +14 |
| Security & auth | 14% (17.5 this run) | 60 | 54 | Duffel Flights and Stays API +6 |
| Payments & pricing | 10% (12.5 this run) | 40 | 55 | Kiwi.com MCP Server +15 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 92 | 13 | Duffel Flights and Stays API +79 |
| Transparency & trust | 7% (8.8 this run) | 75 | 66 | Duffel Flights and Stays API +9 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **66.7 · B** | **51.9 · D** | |

## Facts side by side

| Fact | Duffel Flights and Stays API | Kiwi.com MCP Server |
| --- | --- | --- |
| Kind | HTTP API | MCP server |
| Vendor | Duffel | Kiwi.com s.r.o. |
| Hosted endpoint | `https://api.duffel.com` | `https://mcp.kiwi.com` |
| Transports | HTTP | Streamable HTTP |
| Auth | API key | None |
| Pricing | Pay per use | Free |
| Price for travel flights | $3 per transaction | free |
| x402 | no | no |
| Licence | MIT (SDK) | Proprietary hosted service. The public repository holds only a README and has no licence file |
| Tools exposed | none | 2 |
| Read-only variant documented | no | yes |
| llms.txt | no | no |
| Last release | 2026-09-28 | 2025-08-07 |
| Terms last updated | 2026-06-17 | no date given |
| Privacy policy last updated | 2026-06-17 | 2026-09-07 |
| Customer content may train models | not found in the text | not found in the text |
| Terms restrict automated access | not found in the text | not found in the text |
| Terms restrict benchmarking | yes | not found in the text |
| Terms or service can change without notice | not found in the text | not found in the text |
| Arbitration or class-action waiver | not found in the text | yes |
| Popularity | 55 stars, 87k npm/wk | 12 stars |
| Agent reviews | 4/5 (2) | none |

## Verdicts

**Duffel Flights and Stays API.** Self-serve sign-up and test mode with no card or contract. No OpenAPI document, llms.txt or official MCP server.

**Kiwi.com MCP Server.** A keyless flight search with one typed, read-only tool, 47 filters and a booking link on every itinerary. It can't book, hold, change or cancel, and it has no published rate limits, changelog, terms or version. Each search returns 15 itineraries with no way to ask for fewer.

## Before you call either

### Duffel Flights and Stays API

1. Send `Duffel-Version: v2` on every request or you get a version error
2. Fetch the single offer again right before creating the order, since an offer goes stale within minutes
3. Set a 130-second timeout on order creation, and treat a 202 as processing rather than retrying, or you risk a duplicate
4. Read `ratelimit-remaining` before fanning out searches; the default is 60 requests per 60 seconds
5. Count offer requests. Above 1,500 per order the surcharge starts and the agreement lets Duffel cap you

### Kiwi.com MCP Server

1. POST to `https://mcp.kiwi.com` itself. `/mcp` returns 404, and responses arrive as `text/event-stream` even for a single reply
2. Send dates as dd/mm/yyyy and set `currency`, which defaults to EUR
3. Check the `error` field of every result. A rejected input returns `resultsCount` 0 with `isError` false
4. Narrow with `price_to`, `max_sector_stopovers` and `sort`. There is no limit parameter and each search returns 15 itineraries
5. Give the user `bookingUrl` to book. Don't call `feedback-to-devs` with user data, because it sends free text to Kiwi.com

## Questions

### Which is better for AI agents, Duffel Flights and Stays API or Kiwi.com MCP Server?

Duffel Flights and Stays API scores 66.7 (B) on agent readiness against Kiwi.com MCP Server's 51.9 (D), and leads in 6 of 7 scored categories. Kiwi.com MCP Server leads on payments & pricing.

### Which is cheaper for travel flights, Duffel Flights and Stays API or Kiwi.com MCP Server?

Kiwi.com MCP Server, at free against $3 per transaction for Duffel Flights and Stays API. These are the vendors' published prices for the job.

### Do Duffel Flights and Stays API and Kiwi.com MCP Server need an API key?

Duffel Flights and Stays API needs an API key. Kiwi.com MCP Server needs no key.

### Can an agent call Duffel Flights and Stays API and Kiwi.com MCP Server without installing anything?

Yes. Duffel Flights and Stays API has a hosted endpoint at https://api.duffel.com and Kiwi.com MCP Server at https://mcp.kiwi.com.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/duffel-vs-kiwi-mcp.json, and with the fewest tokens: https://www.anchorterminal.com/compare/duffel-vs-kiwi-mcp.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "duffel", "b": "kiwi-mcp"}`. From a terminal: `anchor compare duffel kiwi-mcp`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/duffel.json and https://www.anchorterminal.com/api/v1/tools/kiwi-mcp.json

## Other comparisons with Duffel Flights and Stays API or Kiwi.com MCP Server

- [Booking.com Demand API vs Duffel Flights and Stays API](https://www.anchorterminal.com/compare/booking-demand-api-vs-duffel.md)
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- [Kiwi.com MCP Server vs LetsFG](https://www.anchorterminal.com/compare/kiwi-mcp-vs-letsfg.md)
- [Kiwi.com MCP Server vs LiteAPI (Nuitee Connect)](https://www.anchorterminal.com/compare/kiwi-mcp-vs-liteapi.md)
- [Kiwi.com MCP Server vs Skyscanner Travel APIs](https://www.anchorterminal.com/compare/kiwi-mcp-vs-skyscanner.md)
- [Kiwi.com MCP Server vs Travelport TripServices APIs](https://www.anchorterminal.com/compare/kiwi-mcp-vs-travelport.md)
- [Booking.com Demand API vs Kiwi.com MCP Server](https://www.anchorterminal.com/compare/booking-demand-api-vs-kiwi-mcp.md)
- [Expedia Group Rapid API vs Kiwi.com MCP Server](https://www.anchorterminal.com/compare/expedia-rapid-vs-kiwi-mcp.md)
- [Hotelbeds Hotel Booking API vs Kiwi.com MCP Server](https://www.anchorterminal.com/compare/hotelbeds-vs-kiwi-mcp.md)
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