Open JSON API for discovering L402 paywalled APIs; powers the API Hub website, MCP registry, and llms.txt.

Overview

The bolthub directory API (REST paths under /directory on the API host) is an open, unauthenticated JSON API for discovering L402 paywalled APIs. It powers the API Hub website, the MCP registry, and the llms.txt feed. Third-party tools and agents can query it directly.

Base URL: https://api.bolthub.ai/directory

All endpoints return JSON and require no authentication.

Endpoints

List APIs

GET /directory

Returns a list of active APIs. Results are capped to the limit value per response.

Parameter	Type	Default	Description
`search`	string	-	Full-text search across names, slugs, descriptions, tags, and endpoint paths
`tag`	string	-	Filter by tag (case-insensitive)
`page`	number	1	Page number (1-1000)
`limit`	number	50	Results per page (max 50)
`sort`	string	`relevance`	`relevance` or `recent`

Pagination applies to managed (hosted) directory entries. External listings are merged into results and may appear inconsistently across pages when combined with high page numbers.

Response:

{
  "entries": [
    {
      "slug": "bitcoin-data",
      "name": "Bitcoin Market Data",
      "description": "Real-time Bitcoin price data and block info.",
      "tags": ["bitcoin", "finance"],
      "gatewayDomain": "https://bitcoin-data.gw.bolthub.ai",
      "endpointCount": 2,
      "quality": {
        "isHealthy": true,
        "uptimePercentage": 99.8,
        "avgResponseTimeMs": 145
      },
      "endpoints": [
        {
          "path": "/v1/prices",
          "method": "GET",
          "title": "Current BTC Price",
          "description": "Get the current Bitcoin price in USD, EUR, and GBP.",
          "docsUrl": null,
          "pricingModel": "per_request",
          "priceSats": 5,
          "tokenBudget": null,
          "durationMinutes": null,
          "unitCostSats": null,
          "freeTryEnabled": true,
          "exampleRequest": { "query": { "currency": "USD" } },
          "exampleResponse": { "USD": 97250, "EUR": 89100 }
        }
      ]
    }
  ],
  "tags": ["bitcoin", "finance", "weather", "ai"],
  "total": 12,
  "hasMore": false
}

Get API details

GET /directory/:slug

Returns full details for a specific API, including the wallet pubkey for NWC Zap verification.

Response:

Same shape as a single entry from the list response, plus:

{
  "walletPubkey": "abc123...",
  "isExternal": false
}

For external (non-hosted) listings, isExternal is true and walletPubkey is null.

Get MCP config

GET /directory/:slug/mcp-config

Returns a ready-to-paste MCP client config for the given API.

JSON Feed

GET /directory/feed.json

Returns a JSON Feed 1.1 of recently listed APIs. Subscribe to this feed to get notified when new APIs are added.

Each item includes a _bolthub extension with structured data:

{
  "_bolthub": {
    "slug": "bitcoin-data",
    "gateway": "https://bitcoin-data.gw.bolthub.ai",
    "endpointCount": 2,
    "endpoints": [
      { "method": "GET", "path": "/v1/prices", "pricingModel": "per_request", "priceSats": 5 }
    ]
  }
}

Machine-readable discovery

llms.txt

GET https://bolthub.ai/llms.txt

A text summary of the marketplace for AI crawlers and LLMs, following the llms.txt convention. Includes usage instructions, pricing models, and the top 20 APIs.

llms-full.txt

GET https://bolthub.ai/llms-full.txt

Extended version with all listed APIs and full endpoint details.

Per-gateway discovery

Each API gateway exposes its own discovery endpoints:

URL	Description
`https://{slug}.gw.bolthub.ai/.well-known/l402-gateway.json`	L402 metadata, endpoints, pricing, MCP config URL
`https://{slug}.gw.bolthub.ai/.well-known/openapi.json`	OpenAPI 3.1 spec with `x-l402-pricing` extensions
`https://{slug}.gw.bolthub.ai/.well-known/mcp.json`	MCP server config for the bridge

Quality signals

The quality object on each directory entry provides health and performance data:

Field	Type	Description
`isHealthy`	boolean	All endpoints are currently reachable
`uptimePercentage`	number \| null	7-day average uptime percentage (0-100)
`avgResponseTimeMs`	number \| null	Average response time from health probes in milliseconds

These are computed from automated health checks that run every 5 minutes against all active endpoints.

Pricing models

The pricingModel field indicates how the endpoint is priced:

Model	Fields	Description
`per_request`	`priceSats`	Fixed sats per call
`per_kb`	`priceSats`, `unitCostSats`	Deposit + sats per KB of response
`token_bucket`	`priceSats`, `tokenBudget`	One payment for N requests
`time_pass`	`priceSats`, `durationMinutes`	One payment for N minutes
`metered`	`priceSats`, `unitCostSats`	Deposit + per-request deduction

Rate limits

The directory API is rate-limited per IP address:

100 requests per minute per endpoint path.
300 requests per minute global cap across all API paths.

Exceeding either limit returns a 429 Too Many Requests response. Cache responses where possible. The list and category endpoints return data that changes infrequently (new APIs are added at most a few times per day).

Directory API