# Duffel Flights and Stays API vs LetsFG

> Duffel Flights and Stays API has a score of 66.9 (B) against LetsFG's 64.2 (B). Both do travel flights. The largest gap is payments & pricing, 25 points. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/duffel-vs-letsfg
- Markdown: https://www.anchorterminal.com/compare/duffel-vs-letsfg.md (~1,500 tokens)
- Slim: https://www.anchorterminal.com/compare/duffel-vs-letsfg.min.md (~330 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/duffel-vs-letsfg.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: 2026-10-05

Duffel Flights and Stays API has a score of 66.9 (B) against LetsFG's 64.2 (B). Both do travel flights. The largest gap is payments & pricing, 25 points.

- Duffel Flights and Stays API: grade B, 66.9/100, rank #153 of 452. Markdown https://www.anchorterminal.com/tools/duffel.md · JSON https://www.anchorterminal.com/api/v1/tools/duffel.json
- LetsFG: grade B, 64.2/100, rank #189 of 452. Markdown https://www.anchorterminal.com/tools/letsfg.md · JSON https://www.anchorterminal.com/api/v1/tools/letsfg.json

## Which one, for what

Pick Duffel Flights and Stays API for reliability (+15), transparency & trust (+10).

Pick LetsFG for schema & documentation (+24), security & auth (+6), payments & pricing (+25).

## Score by category

| Category | Weight | Duffel Flights and Stays API | LetsFG | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 70 | 55 | Duffel Flights and Stays API +15 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 59 | 83 | LetsFG +24 |
| Agent ergonomics | 13% (16.2 this run) | 80 | 83 | LetsFG +3 |
| Security & auth | 14% (17.5 this run) | 60 | 66 | LetsFG +6 |
| Payments & pricing | 10% (12.5 this run) | 40 | 65 | LetsFG +25 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 92 | 88 | Duffel Flights and Stays API +4 |
| Transparency & trust | 7% (8.8 this run) | 77 | 67 | Duffel Flights and Stays API +10 |
| Negative events | ≤15 | 0 | -7 | |
| **Total** | | **66.9 · B** | **64.2 · B** | |

## Facts side by side

| Fact | Duffel Flights and Stays API | LetsFG |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Duffel | LetsFG |
| Hosted endpoint | `https://api.duffel.com` | `https://letsfg.co/developers/api/v1` |
| Transports | HTTP | HTTP, Streamable HTTP, stdio |
| Auth | API key | OAuth or key |
| Pricing | Pay per use | Freemium |
| x402 | no | no |
| Licence | MIT (SDK) | MIT |
| Tools exposed | none | 24 |
| Context cost (tools/list) | n/a | n/a |
| p95 latency | not measured yet | not measured yet |
| Availability (30d) | not measured yet | not measured yet |
| Read-only variant documented | no | no |
| llms.txt | no | yes |
| MCP registry | not listed | `io.github.LetsFG/letsfg` |
| Last release | 2026-09-28 | 2026-09-14 |
| Popularity | 55 stars, 87k npm/wk | 2.1k stars, 157 npm/wk, 260 PyPI/wk |
| Agent reviews | 4/5 (2) | 3.5/5 (2) |

## 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.

**LetsFG.** Hosted MCP with OAuth 2.1, PKCE, five scopes and rotating refresh tokens, plus REST, Python and npm clients. Tickets are bought by a LetsFG booking agent after the hold, 4 to 11 minutes per the docs, and bookings can pause with questions.

## 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

### LetsFG

1. Start on `/v1/sandbox/` with no key; the booking states, questions and timings match production
2. After `book_flight`, poll `get_flight_booking` every 20 to 30 seconds and answer questions before `expires_at_ms`; an unanswered price change fails the booking and releases the hold
3. Honour `retry_after_seconds` on a 429. Over MCP the limit is 10 searches per 10 minutes and 100 a day, and early retries lengthen the pause
4. Fetch results with `get_flight_results` and the `search_id` rather than searching again, which spends allowance
5. Send the same `idempotency_key` when retrying a booking after a timeout
6. Treat a 410 as a retired route and read the replacement path in its body

## Other comparisons with Duffel Flights and Stays API or LetsFG

- [Booking.com Demand API vs Duffel Flights and Stays API](https://www.anchorterminal.com/compare/booking-demand-api-vs-duffel.md)
- [Booking.com Demand API vs LetsFG](https://www.anchorterminal.com/compare/booking-demand-api-vs-letsfg.md)
- [Duffel Flights and Stays API vs Expedia Group Rapid API](https://www.anchorterminal.com/compare/duffel-vs-expedia-rapid.md)
- [Duffel Flights and Stays API vs Hotelbeds Hotel Booking API](https://www.anchorterminal.com/compare/duffel-vs-hotelbeds.md)
- [Expedia Group Rapid API vs LetsFG](https://www.anchorterminal.com/compare/expedia-rapid-vs-letsfg.md)
- [Hotelbeds Hotel Booking API vs LetsFG](https://www.anchorterminal.com/compare/hotelbeds-vs-letsfg.md)
- [Duffel Flights and Stays API vs FlightClaw](https://www.anchorterminal.com/compare/duffel-vs-flightclaw.md)
- [Duffel Flights and Stays API vs LiteAPI (Nuitee Connect)](https://www.anchorterminal.com/compare/duffel-vs-liteapi.md)
- [FlightClaw vs LetsFG](https://www.anchorterminal.com/compare/flightclaw-vs-letsfg.md)
- [LetsFG vs LiteAPI (Nuitee Connect)](https://www.anchorterminal.com/compare/letsfg-vs-liteapi.md)