# Airlines Reference — Route Between Two Airports

> Airlines Reference — Route Between Two Airports is a paid API for AI agents from airlines-reference.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-11-02).

Returns the list of airlines that operate routes between two airports (by IATA or ICAO code), in both directions, from the OpenFlights routes snapshot.

## Facts

- Endpoint: GET https://airlines-reference.x402tookit.com/airline-route-between?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-11-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/airlines-reference-route-between-two-airports-2df15487
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_JT-pXNHTqn5yQM_rLK4u5

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability airlines-reference-route-between-two-airports-2df15487
```

Example prompt: Which airlines flew between JFK and LHR according to the OpenFlights routes snapshot? I need the carrier names, their IATA and ICAO codes, and how many routes each had in both directions.

## When to prefer this

Use this endpoint when you need to discover which airlines historically served a route between two airports, based on the OpenFlights routes dataset. Ideal for travel research tools, aviation analytics, or data enrichment pipelines that need carrier lists per route. Prefer this over live flight search APIs when historical or reference data is sufficient and real-time pricing/availability is not needed.

## Known failure modes

- Invalid or unrecognized airport code returns empty airlines array or error
- Route not found in snapshot returns empty results (snapshot is from ~2017 and may be outdated)
- Missing required 'from' or 'to' query parameters returns a validation error
- Snapshot data may not reflect current airline operations (historical data only)
- ICAO vs IATA code mismatch may yield no results if the wrong format is used for a given airport

## How this service works

Airlines listed on a route between two airport codes (JFK, LHR) in the old OpenFlights routes snapshot, both directions.

## Output

Returns a structured object containing: a list of airlines operating routes between the two specified airports (each with IATA code, ICAO code, name, alias, callsign, country, active flag, route counts in each direction, and total routes in the snapshot), plus a summary text, verdict, data source attribution, snapshot date, degraded flag, disclaimer, and any reasons or not-checked notes.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "from",
      "to"
     ],
     "properties": {
      "to": {
       "type": "string",
       "description": "Destination airport code (LHR)"
      },
      "from": {
       "type": "string",
       "description": "Origin airport code, IATA (JFK) or ICAO (KJFK) as used in the routes file"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "to": {
       "type": [
        "null",
        "string"
       ]
      },
      "asOf": {
       "type": [
        "null",
        "string"
       ]
      },
      "from": {
       "type": [
        "null",
        "string"
       ]
      },
      "source": {
       "type": [
        "null",
        "string"
       ]
      },
      "reasons": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "summary": {
       "type": [
        "null",
        "string"
       ]
      },
      "verdict": {
       "type": [
        "null",
        "string"
       ]
      },
      "airlines": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "object",
        "properties": {
         "iata": {
          "type": [
           "null",
           "string"
          ]
         },
         "icao": {
          "type": [
           "null",
           "string"
          ]
         },
         "name": {
          "type": [
           "null",
           "string"
          ]
         },
         "alias": {},
         "active": {
          "type": [
           "boolean",
           "null"
          ]
         },
         "country": {
          "type": [
           "null",
           "string"
          ]
         },
         "listing": {
          "type": [
           "null",
           "string"
          ]
         },
         "callsign": {
          "type": [
           "null",
          
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/airlines-reference-route-between-two-airports-2df15487/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from airlines-reference.x402tookit.com](https://www.zero.xyz/host/airlines-reference.x402tookit.com/llms.txt)