Letsfg

LetsFG

Agent-native flight search and booking. Hundreds of airlines plus the major booking sites, Compares airlines and the major booking sites in one pass, with per-flight reliability history.

Three-step flow: Search (free) → Unlock (free) → Book (ticket price only)

Why Use This

• Hundreds of airlines in parallel — Ryanair, EasyJet, Wizz Air, Southwest, AirAsia, Norwegian, Qantas, LATAM, Spirit, Frontier, IndiGo, VietJet, and more
• Zero price bias — no demand inflation, no cookie tracking, no surge pricing. Raw airline prices every time
• One tool call — replaces thousands of tokens of browser automation, scraping, and HTML parsing
• Structured JSON — prices, times, durations, stops, conditions, airline names

Setup

Option A: MCP Server (Recommended for Claude Desktop / Cursor / VS Code)

Remote (no install):

{
  "mcpServers": {
    "letsfg": {
      "url": "https://letsfg.co/developers/api/mcp",
      "headers": {
        "X-API-Key": "trav_your_api_key"
      }
    }
  }
}

Local (stdio):

{
  "mcpServers": {
    "letsfg": {
      "command": "npx",
      "args": ["-y", "letsfg-mcp"],
      "env": {
        "LETSFG_API_KEY": "trav_your_api_key"
      }
    }
  }
}

Option B: CLI

pip install letsfg
letsfg search LHR BCN 2026-06-15

Option C: Python SDK

from letsfg import LetsFG
bt = LetsFG(api_key="trav_...")
flights = bt.search("LHR", "JFK", "2026-04-15")

Get an API Key (Free)

letsfg register --name my-agent --email agent@example.com

Then connect a payment method (nothing is charged; there is no unlock step):

letsfg connect-payment   # prints a link to open in a browser

Workflow

1. Resolve Locations First

City names are ambiguous — "London" = LHR, LGW, STN, LCY, LTN. Always resolve first:

letsfg locations "London"
# LON  London (all airports)
# LHR  Heathrow
# LGW  Gatwick
# ...

locations = bt.resolve_location("London")
# Use city code "LON" for all airports, or specific airport "LHR"

2. Search (FREE, Unlimited)

flights = bt.search("LON", "BCN", "2026-04-01")
# Round trip:
flights = bt.search("LON", "BCN", "2026-04-01", return_date="2026-04-08")
# Multi-passenger:
flights = bt.search("LHR", "SIN", "2026-06-01", adults=2, children=1, cabin_class="C")

letsfg search LON BCN 2026-04-01 --return 2026-04-08 --sort price --json

Search returns structured offers:

{
  "passenger_ids": ["pas_0"],
  "total_results": 47,
  "offers": [{
    "id": "off_xxx",
    "price": 89.50,
    "currency": "EUR",
    "airlines": ["Ryanair"],
    "route": "STN → BCN",
    "duration_seconds": 7800,
    "stopovers": 0,
    "conditions": {
      "refund_before_departure": "not_allowed",
      "change_before_departure": "allowed_with_fee"
    }
  }]
}

3. Unlock — RETIRED 2026-09-08

There is no unlock step on either lane any more, and the route answers 410 Gone. Unlock existed to confirm a live price before charging; booking now HOLDS the fare and captures only against a real airline PNR, so a moved price surfaces as a question to accept or decline rather than a surprise charge. Call book_flight (PFS) or POST /flights/book (Developer API) directly.

# unlock() raises LetsFGError(410) locally — it does not call the server. Book instead:
booking = bt.book_and_wait(
    offer_id=flights.cheapest.id,
    search_id=flights.search_id,
    passengers=[{"given_name": "John", "family_name": "Doe", "born_on": "1990-01-15"}],
    contact_email="you@example.com",
)
print(booking)

letsfg unlock off_xxx

Note: Confirmed price may differ from search price (airline prices change in real-time). Inform the user if price changed significantly.

4. Book (Ticket Price Only)

booking = bt.book(
    offer_id=unlocked.offer_id,
    passengers=[{
        "id": flights.passenger_ids[0],
        "given_name": "John",
        "family_name": "Doe",
        "born_on": "1990-01-15",
        "gender": "m",
        "title": "mr",
        "email": "john@example.com"
    }],
    contact_email="john@example.com",
    idempotency_key="unique-booking-key-123"
)
print(f"Booked! PNR: {booking.booking_reference}")

Critical Rules

1. Use REAL passenger details — airlines send e-tickets to the contact email. Names must match passport/ID exactly. Never use placeholder or fake data.
2. Always provide idempotency_key when booking — prevents duplicate reservations if the agent retries on timeout.
3. Resolve locations before searching — "New York" = JFK, LGA, EWR, NYC. Use resolve_location() first.
4. Search is free — search as many routes, dates, and cabin classes as needed.
5. Map passenger IDs — search returns passenger_ids. Each booking passenger must include the correct id.

Best Practices

Search Wide, Unlock Narrow

# Compare multiple dates (all FREE)
dates = ["2026-04-01", "2026-04-02", "2026-04-03"]
best = None
for date in dates:
    result = bt.search("LON", "BCN", date)
    if result.offers and (best is None or result.cheapest.price < best[1].price):
        # keep the result too: an offer is bookable only inside the search that produced it
        best = (date, result.cheapest, result.search_id)

# Book only the winner — there is no unlock step
booking = bt.book(best[1].id, passengers=[{...}], contact_email="you@example.com",
                  search_id=best[2])

Filter Before Booking

flights = bt.search("LHR", "JFK", "2026-06-01", limit=50)

candidates = [
    o for o in flights.offers
    if o.outbound.stopovers == 0
    and o.outbound.total_duration_seconds < 10 * 3600
]

if candidates:
    best = min(candidates, key=lambda o: o.price)
    booking = bt.book(best.id, passengers=[{...}], contact_email="you@example.com",
                      search_id=flights.search_id)

Error Handling

from letsfg import LetsFG, OfferExpiredError, PaymentRequiredError

try:
    booking = bt.book(offer_id, passengers=[{...}], contact_email="you@example.com",
                      search_id=search_id)
except OfferExpiredError:
    # Airline sold the seats — search again and book from the fresh results
    flights = bt.search(origin, dest, date)
except PaymentRequiredError:
    # No card on file — connect one (or pay via MPP crypto on the 402 challenge)
    print("Connect a card:", bt.connect_payment()["connect_url"])

Search Flags

Safety

Reference Files

Load only when needed:

Links

• API Docs: https://letsfg.co/developers/api/docs
• GitHub: https://github.com/LetsFG/LetsFG
• PyPI: https://pypi.org/project/letsfg/
• npm SDK: https://www.npmjs.com/package/letsfg
• npm MCP: https://www.npmjs.com/package/letsfg-mcp