Chains API

A Node.js API query service built with Fastify that indexes and provides access to blockchain chain data from multiple sources. Also available as an MCP (Model Context Protocol) server for AI assistants.

Code Quality & Testing

This project maintains high code quality standards through:

• Comprehensive Testing: Includes unit tests, integration tests, and fuzz testing

  • 300+ test cases covering all core functionality
  • Continuous integration with automated test runs on every push
  • See Testing Documentation for details

• SonarQube Analysis: Automated code quality scanning on every commit

  • Enforces code coverage requirements (≥80%)
  • Monitors code duplication (≤3%)
  • Tracks cognitive complexity and code smells

All changes are validated through GitHub Actions CI/CD pipeline, ensuring code quality and test coverage before deployment.

Features

• Multi-Source Data Aggregation: Combines data from multiple blockchain registries:

  • The Graph Networks Registry
  • Chainlist RPCs
  • Chain ID Network (for basic chain data and L2 relation indexing using parent field)
  • SLIP-0044 Coin Types

• Fast API: Built with Fastify for high performance

• MCP Server: Available as a Model Context Protocol server for AI assistants

• Indexed Data: Efficient querying with indexed chain data

• Search Capabilities: Search chains by name, ID, or other attributes

• RESTful Endpoints: Clean and intuitive API design

• Chain Relations & Tags: Automatic indexing of chain relationships and tags

  • Tags: Testnet, L2, Beacon
  • Relations: testnetOf, mainnetOf, l2Of, parentOf, beaconOf with resolved chain IDs
  • Example: Base Sepolia (84532) is tagged as Testnet and L2, with relations to Base (8453) and Sepolia (11155111)
  • Reverse relations: Mainnets have mainnetOf relations pointing to testnets, L1s have parentOf relations pointing to L2s

• RPC Health Monitoring: Automatic background monitoring of RPC endpoints to identify working and failed nodes.

• Data Validation: Built-in validation tools to identify data inconsistencies between multiple sources (e.g., The Graph registry vs. Chainlist).

Installation

Using npm

npm install

Using Docker

Pull from GitHub Container Registry

Pre-built Docker images are automatically published to GitHub Container Registry (GHCR) on every push to the main branch:

# Pull the latest image
docker pull ghcr.io/johnaverse/chains-api:latest

# Or pull a specific version
docker pull ghcr.io/johnaverse/chains-api:v1.1.1

Build Docker image locally

# Build the image
docker build -t chains-api .

# Or using docker compose
docker compose build

Usage

Running with Docker

Run the REST API server

# Using pre-built image from GHCR
docker run -d -p 3000:3000 --name chains-api ghcr.io/johnaverse/chains-api:latest

# Or using locally built image
docker run -d -p 3000:3000 --name chains-api chains-api

# With custom environment variables
docker run -d -p 3000:3000 \
  -e PORT=3000 \
  -e HOST=0.0.0.0 \
  --name chains-api \
  ghcr.io/johnaverse/chains-api:latest

The API will be available at http://localhost:3000.

Run the MCP HTTP server

docker run -d -p 3001:3001 \
  --name chains-api-mcp \
  ghcr.io/johnaverse/chains-api:latest \
  node mcp-server-http.js

The MCP HTTP server will be available at http://localhost:3001.

Using Docker Compose

A docker-compose.yml file is included in the repository that runs both the REST API server on port 3000 and the MCP HTTP server on port 3001:

docker compose up -d

To use pre-built images from GHCR instead of building locally, modify the docker-compose.yml to use image: ghcr.io/johnaverse/chains-api:latest instead of build: .

The default configuration:

services:
  chains-api:
    build: .
    image: chains-api:latest
    container_name: chains-api
    ports:
      - "3000:3000"
    environment:
      - PORT=3000
      - HOST=0.0.0.0
    restart: unless-stopped
    healthcheck:
      test:
        [
          "CMD",
          "node",
          "-e",
          "require('http').get('http://localhost:3000/health', (r) => { process.exit(r.statusCode === 200 ? 0 : 1) })",
        ]
      interval: 30s
      timeout: 10s
      retries: 3
      start_period: 5s

  chains-api-mcp:
    build: .
    image: chains-api:latest
    container_name: chains-api-mcp
    command: node mcp-server-http.js
    ports:
      - "3001:3001"
    environment:
      - MCP_PORT=3001
      - MCP_HOST=0.0.0.0
    restart: unless-stopped
    healthcheck:
      test:
        [
          "CMD",
          "node",
          "-e",
          "require('http').get('http://localhost:3001/health', (r) => { process.exit(r.statusCode === 200 ? 0 : 1) })",
        ]
      interval: 30s
      timeout: 10s
      retries: 3
      start_period: 5s

Running with npm

REST API Server

Start the server

npm start

The server will start on http://localhost:3000 by default.

Development mode (with auto-reload)

npm run dev

Using a Proxy (Optional)

To route all outbound requests through a proxy server, set the PROXY_URL environment variable:

# Using a proxy without authentication
PROXY_URL=http://proxy.example.com:8080 npm start

# Using a proxy with authentication
PROXY_URL=http://user:pass@proxy.example.com:8080 npm start

When configured, the proxy will be used for:

• All RPC endpoint health checks and monitoring
• Fetching data from external sources (The Graph, Chainlist, etc.)

The proxy configuration is optional and disabled by default. See the Environment Variables section for more details.

MCP Server (for AI Assistants)

The Chains API can also be used as an MCP (Model Context Protocol) server, allowing AI assistants like Claude to query blockchain chain data directly. Two transport modes are supported:

1. Stdio Mode (for local AI assistants like Claude Desktop)
2. HTTP Mode (for external clients like n8n, Make.com, etc.)

Running the MCP Server (Stdio Mode)

For local use with Claude Desktop and similar applications:

npm run mcp

Or directly with Node.js:

node mcp-server.js

Running the MCP HTTP Server (Network Mode)

For external clients that need HTTP access:

npm run mcp:http

Or directly with Node.js:

node mcp-server-http.js

The HTTP server will start on http://0.0.0.0:3001 by default (configurable via MCP_PORT and MCP_HOST environment variables).

Endpoints:

• POST /mcp - MCP protocol endpoint for tool calls
• DELETE /mcp - Session termination endpoint
• GET /health - Health check
• GET / - Server information

Example HTTP MCP usage with curl:

# Initialize a session
curl -X POST http://localhost:3001/mcp \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -d '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"my-client","version":"1.1.1"}}}'

# Extract session ID from the mcp-session-id header, then call a tool:
curl -X POST http://localhost:3001/mcp \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -H "mcp-session-id: <session-id>" \
  -d '{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"get_chain_by_id","arguments":{"chainId":1}}}'

MCP Server Configuration (Stdio Mode)

To use the Chains API MCP server with Claude Desktop or other MCP clients, add it to your MCP settings configuration file:

For Claude Desktop (~/Library/Application Support/Claude/claude_desktop_config.json on macOS):

{
  "mcpServers": {
    "chains-api": {
      "command": "node",
      "args": ["/path/to/chains-api/mcp-server.js"]
    }
  }
}

Or if you've installed the package globally:

{
  "mcpServers": {
    "chains-api": {
      "command": "chains-api-mcp"
    }
  }
}

Available MCP Tools

The MCP server provides the following tools for querying blockchain chain data:

• get_chains: Get all blockchain chains, optionally filtered by tag (Testnet, L2, or Beacon)
• get_chain_by_id: Get detailed information about a specific blockchain chain by its chain ID
• search_chains: Search for blockchain chains by name or other attributes
• get_endpoints: Get RPC, firehose, and substreams endpoints for a specific chain or all chains
• get_relations: Get chain relationships (testnet/mainnet, L2/L1, etc.) for a specific chain or all chains
• get_slip44: Get SLIP-0044 coin type information by coin type ID or all coin types

Each tool returns JSON data that can be used by AI assistants to answer questions about blockchain networks.

Environment Variables

Server Configuration

• PORT: REST API server port (default: 3000)
• HOST: REST API server host (default: 0.0.0.0)
• MCP_PORT: MCP HTTP server port (default: 3001)
• MCP_HOST: MCP HTTP server host (default: 0.0.0.0)

Proxy Configuration (Optional)

• PROXY_URL: HTTP/HTTPS proxy URL for all outbound requests (default: empty/disabled)
  • Example: http://proxy.example.com:8080
  • With authentication: http://user:pass@proxy.example.com:8080
  • When set, all RPC requests and data source fetching will route through this proxy
  • Leave empty or unset to disable proxy support

Rate Limiting

• RATE_LIMIT_MAX: Maximum requests per window for global endpoints (default: 100)
• RATE_LIMIT_WINDOW_MS: Rate limit window in milliseconds (default: 60000 = 1 minute)
• RELOAD_RATE_LIMIT_MAX: Maximum /reload requests per window (default: 5)
• SEARCH_RATE_LIMIT_MAX: Maximum /search requests per window (default: 30)

RPC Health Check

• RPC_CHECK_TIMEOUT_MS: Timeout per RPC health check call in milliseconds (default: 8000)
• RPC_CHECK_CONCURRENCY: Number of parallel RPC health checks (default: 8)
• MAX_ENDPOINTS_PER_CHAIN: Maximum RPC endpoints tested per chain (default: 5)

Data Cache

• DATA_CACHE_ENABLED: Enable disk-backed startup cache (default: true)
• DATA_CACHE_FILE: Snapshot file path used for stale-first startup (default: .cache/chains-api-data.json)

Assistant (Optional)

An LLM chat assistant over the whole registry plus live incidents, exposed at POST /assistant/chat and consumed by the dashboard's floating chat overlay (corner button, available on every view). It runs a tool-use loop against any OpenAI-compatible server (Ollama, vLLM, LM Studio) and stays disabled until configured:

ollama pull qwen3
ASSISTANT_LLM_URL=http://localhost:11434 npm start

• ASSISTANT_LLM_URL: OpenAI-compatible LLM base URL (default: empty = assistant disabled)
• ASSISTANT_LLM_API_KEY: Bearer token for key-protected servers such as OpenAI or OpenRouter (default: empty — not needed for a plain Ollama)
• ASSISTANT_MODEL: Model name passed to /v1/chat/completions (default: qwen3)
• ASSISTANT_MAX_TOOL_ITERATIONS: Hard cap on LLM round-trips per request (default: 6)
• ASSISTANT_TIMEOUT_MS: Overall per-request deadline (default: 60000)
• ASSISTANT_MAX_TOKENS: max_tokens per LLM call (default: 1024)
• ASSISTANT_RATE_LIMIT_MAX: Maximum /assistant/chat requests per window per IP (default: 10)
• ASSISTANT_TOPIC_GUARD: Pre-classify each question with a cheap extra LLM call and refuse off-topic ones before the tool loop runs; fails open if the classifier misbehaves (default: true)
• ASSISTANT_FALLBACK_LLM_URL / ASSISTANT_FALLBACK_MODEL / ASSISTANT_FALLBACK_LLM_API_KEY: Optional backup provider — see below.

Fallback provider (optional)

Configure a second OpenAI-compatible server and the assistant survives the primary going down:

# Example 1: big model with a smaller local backup on another port
ASSISTANT_LLM_URL=http://10.0.0.47:8000        ASSISTANT_MODEL=qwen3-27b \
ASSISTANT_FALLBACK_LLM_URL=http://localhost:11434 ASSISTANT_FALLBACK_MODEL=qwen3:8b \
npm start

# Example 2: local primary with a hosted API as the backup
ASSISTANT_LLM_URL=http://localhost:11434       ASSISTANT_MODEL=qwen3 \
ASSISTANT_FALLBACK_LLM_URL=https://openrouter.ai/api ASSISTANT_FALLBACK_MODEL=qwen/qwen3-32b \
ASSISTANT_FALLBACK_LLM_API_KEY=sk-or-... \
npm start

Behavior:

• A chat run starts on the primary; if any LLM call fails (connection refused, timeout, HTTP error), the run switches to the backup and stays on it for the rest of that run. The next chat tries the primary again — no manual reset needed after recovery.
• The switch is visible: the thinking trace shows a "switching to backup model" step, the answer JSON carries viaFallback: true, and the dashboard bubble gets a backup model badge.
• While an untried backup remains, a single primary attempt is capped at 60s so an unresponsive primary can't consume the whole request budget before failover.
• GET /assistant reports reachable: true if either provider answers, so the dashboard pill stays green during a primary outage.
• The backup must handle tool/function calling for full functionality; if it's a weaker model, expect simpler answers rather than failures — all the harness defenses (arg validation, iteration caps) apply to it too.
• ASSISTANT_FALLBACK_MODEL defaults to ASSISTANT_MODEL when unset, and the key is only needed for auth-protected backups.
• LIVE_INCIDENTS_URL: Live incident feed for the get_live_incidents tool (default: https://chains-status-news.johnaverse.cc)
• FORUM_NEWS_URL: Forum/governance news feed for the get_forum_news tool (default: https://chains-forum-news.johnaverse.cc)

Other

• BODY_LIMIT: Maximum request body size in bytes (default: 1048576 = 1 MB)
• MAX_PARAM_LENGTH: Maximum URL parameter length (default: 200)
• MAX_SEARCH_QUERY_LENGTH: Maximum search query length (default: 200)
• CORS_ORIGIN: Allowed CORS origins (default: * for all origins)

See .env.example for a complete list of environment variables with example values.

API Endpoints

GET /

Get API information and available endpoints.

Response:

{
  "name": "Chains API",
  "version": "1.1.1",
  "description": "API query service for blockchain chain data from multiple sources",
  "endpoints": { ... },
  "dataSources": [ ... ]
}

GET /health

Health check and data status.

Response:

{
  "status": "ok",
  "dataLoaded": true,
  "lastUpdated": "2026-02-07T14:13:42.104Z",
  "totalChains": 1234
}

GET /assistant

Assistant availability probe: {"enabled": true, "model": "qwen3"} (enabled: false when no LLM is configured).

POST /assistant/chat

Chat with the assistant. Stateless — send the full conversation each turn; the assistant may reply with a clarifying question (e.g. mainnet vs testnet) that you answer in a follow-up message.

Fast answers return 200 with the result directly. Runs that outlive the sync window (ASSISTANT_SYNC_WAIT_MS, default 8s — typical for large local models) return 202 {"jobId", "status": "running", "pollAfterMs"}; poll GET /assistant/chat/:jobId until status is done (result fields included) or error. This keeps every HTTP request short, so reverse-proxy/CDN timeouts never kill a slow LLM run.

Request:

{
  "messages": [{ "role": "user", "content": "is base healthy right now?" }],
  "context": { "view": "networks", "chainId": 8453 }
}

Response:

{
  "reply": "Base mainnet (`8453`): 5/5 monitored RPC endpoints healthy…",
  "toolCalls": [{ "name": "get_rpc_monitor_by_id", "args": { "chainId": 8453 } }],
  "degraded": false,
  "usage": { "promptTokens": 1874, "completionTokens": 96 }
}

Errors: 503 when not configured or the LLM is unreachable, 429 on rate limit, 400 on invalid payloads.

GET /rpc-monitor

Get RPC endpoint monitoring results for all chains. At startup, a background process validates the health of the indexed RPC endpoints.

Response:

{
  "isMonitoring": false,
  "lastUpdated": "2026-02-07T14:13:42.104Z",
  "totalEndpoints": 4236,
  "testedEndpoints": 850,
  "workingEndpoints": 782,
  "results": [
    {
      "chainId": 1,
      "chainName": "Ethereum Mainnet",
      "url": "https://eth.rpc.pinax.network",
      "status": "working",
      "clientVersion": "geth/v1.14.0",
      "blockNumber": 19123456,
      "testedAt": "2026-02-07T14:13:42.104Z"
    },
    ...
  ]
}

GET /rpc-monitor/:id

Get RPC monitoring results for a specific chain by its chain ID.

Example: GET /rpc-monitor/1 (Ethereum)

Response:

{
  "chainId": 1,
  "chainName": "Ethereum Mainnet",
  "totalEndpoints": 15,
  "workingEndpoints": 12,
  "lastUpdated": "2026-02-07T14:13:42.104Z",
  "endpoints": [
    {
      "url": "https://eth.rpc.pinax.network",
      "status": "working",
      "clientVersion": "geth/v1.14.0",
      "blockNumber": 19123456,
      "error": null,
      "testedAt": "2026-02-07T14:13:42.104Z"
    },
    ...
  ]
}

GET /chains

Get all indexed chains.

Query Parameters:

• tag (optional): Filter chains by tag (e.g., Testnet, L2, Beacon)

Example: GET /chains?tag=Testnet

Response:

{
  "count": 1234,
  "chains": [ ... ]
}

Example Chain Object:

{
  "chainId": 80002,
  "name": "Amoy",
  "shortName": "polygonamoy",
  "theGraph-id": "polygon-amoy",
  "fullName": "Polygon Amoy Testnet",
  "caip2Id": "eip155:80002",
  "aliases": ["amoy-testnet", "amoy"],
  "nativeCurrency": {
    "name": "POL",
    "symbol": "POL",
    "decimals": 18
  },
  "explorers": [ ... ],
  "infoURL": "https://polygon.technology/",
  "sources": ["chains", "theGraph"],
  "tags": ["Testnet", "L2"],
  "status": "active",
  "bridges": [
    {
      "url": "https://bridge.polygon.technology/"
    }
  ]
}

Note: Chain info no longer includes rpc or relations fields. Use /endpoints/:id for RPC endpoints and /relations/:id for chain relations.

GET /chains/:id

Get a specific chain by its chain ID.

Example: GET /chains/80002 (Amoy)

Response:

{
  "chainId": 80002,
  "name": "Amoy",
  "shortName": "polygonamoy",
  "theGraph-id": "polygon-amoy",
  "fullName": "Polygon Amoy Testnet",
  "caip2Id": "eip155:80002",
  "aliases": ["amoy-testnet", "amoy"],
  "nativeCurrency": {
    "name": "POL",
    "symbol": "POL",
    "decimals": 18
  },
  "explorers": [
    {
      "name": "polygonscan-amoy",
      "url": "https://amoy.polygonscan.com",
      "standard": "EIP3091"
    }
  ],
  "infoURL": "https://polygon.technology/",
  "sources": ["chains", "theGraph"],
  "tags": ["Testnet", "L2"],
  "status": "active",
  "bridges": [
    {
      "url": "https://bridge.polygon.technology/"
    }
  ]
}

GET /search?q={query}

Search chains by name or ID.

Example: GET /search?q=ethereum

Response:

{
  "query": "ethereum",
  "count": 15,
  "results": [ ... ]
}

GET /endpoints

Get endpoints (RPC, firehose, substreams) for all chains.

Response:

{
  "count": 4236,
  "endpoints": [
    {
      "chainId": 80002,
      "name": "Amoy",
      "rpc": [
        "https://rpc-amoy.polygon.technology",
        "https://polygon-amoy-bor-rpc.publicnode.com",
        ...
      ],
      "firehose": [
        "amoy.firehose.pinax.network:443"
      ],
      "substreams": [
        "amoy.substreams.pinax.network:443"
      ]
    },
    ...
  ]
}

GET /endpoints/:id

Get endpoints (RPC, firehose, substreams) for a specific chain by ID.

Example: GET /endpoints/80002 (Amoy)

Response:

{
  "chainId": 80002,
  "name": "Amoy",
  "rpc": [
    "https://rpc-amoy.polygon.technology",
    "https://polygon-amoy-bor-rpc.publicnode.com",
    "wss://polygon-amoy-bor-rpc.publicnode.com",
    "https://amoy.rpc.service.pinax.network"
  ],
  "firehose": [
    "amoy.firehose.pinax.network:443"
  ],
  "substreams": [
    "amoy.substreams.pinax.network:443"
  ]
}

GET /relations

Get all chain relations data.

Response:

{
  "count": 123,
  "relations": [ ... ]
}

GET /relations/:id

Get relations for a specific chain by ID.

Example: GET /relations/80002

Response:

{
  "chainId": 80002,
  "chainName": "Amoy",
  "relations": [
    {
      "kind": "testnetOf",
      "network": "matic",
      "chainId": 137,
      "source": "theGraph"
    },
    {
      "kind": "l2Of",
      "network": "sepolia",
      "chainId": 11155111,
      "source": "theGraph"
    }
  ]
}

GET /sources

Get status of data sources.

Response:

{
  "lastUpdated": "2026-02-07T14:13:42.104Z",
  "sources": {
    "theGraph": "loaded",
    "chainlist": "loaded",
    "chains": "loaded",
    "slip44": "loaded"
  }
}

GET /export

Export the disk cache snapshot file (DATA_CACHE_FILE) as JSON.

Returns:

• 200 with JSON snapshot content when the file exists
• 404 when the cache file does not exist
• 503 when cache is disabled (DATA_CACHE_ENABLED=false)

Response (example):

{
  "schemaVersion": 1,
  "writtenAt": "2026-02-23T12:34:56.000Z",
  "data": {
    "lastUpdated": "2026-02-23T12:34:56.000Z",
    "indexed": {
      "byChainId": {},
      "byName": {},
      "all": []
    }
  }
}

GET /slip44

Get all SLIP-0044 coin types as JSON. The table from the markdown file is converted to JSON format using "Coin type" as the key (id).

Response:

{
  "count": 1279,
  "coinTypes": {
    "0": {
      "coinType": 0,
      "pathComponent": "0x80000000",
      "symbol": "BTC",
      "coin": "Bitcoin"
    },
    "60": {
      "coinType": 60,
      "pathComponent": "0x8000003c",
      "symbol": "ETH",
      "coin": "Ether"
    }
  }
}

GET /slip44/:coinType

Get a specific SLIP-0044 coin type by its coin type ID.

Example: GET /slip44/60 (Ethereum)

Response:

{
  "coinType": 60,
  "pathComponent": "0x8000003c",
  "symbol": "ETH",
  "coin": "Ether"
}

POST /reload

Reload data from all sources.

Response:

{
  "status": "success",
  "lastUpdated": "2026-02-07T14:13:42.104Z",
  "totalChains": 1234
}

GET /validate

Validate chain data for potential human errors across all three data sources.

This endpoint analyzes the chain data and identifies potential inconsistencies or errors based on the following rules:

1. Rule 1 - Relation Conflicts: Assumes graph relations are always true and finds conflicts with other sources
2. Rule 2 - slip44/Testnet Mismatch: Chains with slip44=1 but isTestnet=false
3. Rule 3 - Name/Tag Mismatch: Chain full names containing "Testnet" or "Devnet" but not tagged as Testnet
4. Rule 4 - Sepolia/Hoodie Networks: Chains containing "sepolia" or "hoodie" keywords but not identifying as L2 or having no relations
5. Rule 5 - Status Conflicts: Deprecated status conflicts across different sources
6. Rule 6 - Goerli Deprecation: Chains containing "Goerli" keyword but not marked as deprecated

Response:

{
  "totalErrors": 85,
  "summary": {
    "rule1": 3,
    "rule2": 57,
    "rule3": 16,
    "rule4": 1,
    "rule5": 1,
    "rule6": 7
  },
  "errorsByRule": {
    "rule1_relation_conflicts": [...],
    "rule2_slip44_testnet_mismatch": [...],
    "rule3_name_testnet_mismatch": [...],
    "rule4_sepolia_hoodie_issues": [...],
    "rule5_status_conflicts": [...],
    "rule6_goerli_not_deprecated": [...]
  },
  "allErrors": [...]
}

Example Error Object:

{
  "rule": 6,
  "chainId": 5,
  "chainName": "Goerli",
  "type": "goerli_not_deprecated",
  "message": "Chain 5 (Goerli) contains \"Goerli\" but is not marked as deprecated",
  "fullName": "Goerli",
  "status": "active",
  "statusInSources": []
}

Data Structure

Chain Object (from /chains endpoints)

Each chain object returned from /chains and /chains/:id contains:

• chainId: The chain ID (extracted from caip2Id for The Graph data)
• name: Full name of the chain
• shortName: Short name/symbol
• theGraph-id: The Graph network identifier (if available from The Graph)
• fullName: Full network name (if available from The Graph)
• caip2Id: CAIP-2 identifier, e.g., "eip155:1" (if available from The Graph)
• aliases: Alternative names array (if available from The Graph)
• nativeCurrency: Native currency information
• explorers: Array of block explorers
• infoURL: Information URL
• sources: Array of data sources that provided this chain's data
• status: Chain status - defaults to "active" when not present in any data source
• tags: Array of tags (e.g., "Testnet", "L2", "Beacon")
• bridges: Array of bridge URLs (if available from chainlist or chains.json parent.bridges field)

Note: Chain objects no longer include rpc or relations fields. Use /endpoints/:id for RPC endpoints and /relations/:id for relations.

Endpoints Object (from /endpoints endpoints)

Each endpoints object returned from /endpoints and /endpoints/:id contains:

• chainId: The chain ID
• name: Chain name
• rpc: Array of RPC endpoints (strings or objects with url and metadata)
• firehose: Array of The Graph firehose endpoints (if available)
• substreams: Array of The Graph substreams endpoints (if available)

Relations Object (from /relations/:id endpoint)

Relations data contains:

• chainId: The chain ID
• chainName: Chain name
• relations: Array of relations to other chains
  • Each relation contains: kind, network (network ID), optionally chainId (resolved chain ID), and source (data source)
  • Relation kinds: testnetOf, mainnetOf, l2Of, parentOf, beaconOf
  • Relation sources: theGraph, chainlist, chains
  • Reverse relations: After all relations are indexed, reverse relations are automatically created:
    • mainnetOf: Added to mainnets pointing to their testnets (reverse of testnetOf)
    • parentOf: Added to L1 chains pointing to their L2 chains (reverse of l2Of)
  • chainlist relations: When slip44 === 1 or isTestnet === true, finds mainnet by matching tvl field value with chains where isTestnet === false
    • Note: tvl matching is based on chainlist data structure; this field may represent a chain identifier rather than Total Value Locked in some contexts
  • chains.json relations: When parent.type === "L2", creates l2Of relation using parent chain ID extracted from parent.chain field (format: eip155-<chainId>)
    • Example: Mode Testnet (919) has parent: { type: "L2", chain: "eip155-11155111" }, creating a l2Of relation to Sepolia (11155111)

SLIP-0044 Data Structure

Each SLIP-0044 coin type object contains:

• coinType: The coin type number (used as the key/id)
• pathComponent: BIP-0044 path component in hexadecimal
• symbol: Coin symbol
• coin: Full coin name

Documentation

More detailed information about project internals and testing can be found in the docs folder:

• Project Structure: Detailed explanation of files and directories
• Testing: Comprehensive guide to the testing strategy (Unit, Integration, and Fuzz testing)

Contributing

We welcome contributions to the Chains API project! Whether you're fixing bugs, improving documentation, or proposing new features, your contributions are appreciated.

How to Contribute

1. Fork the repository and create your branch from main
2. Make your changes with clear, descriptive commit messages
3. Add or update tests to cover your changes
4. Ensure all tests pass by running npm test
5. Verify code quality - your changes will be automatically scanned by SonarQube
6. Submit a pull request with a clear description of your changes

Code Quality Standards

All contributions must meet our quality standards:

• ✅ All tests must pass (300+ test cases)
• ✅ Code coverage ≥ 80%
• ✅ Code duplication ≤ 3%
• ✅ No critical code smells or security vulnerabilities
• ✅ Cognitive complexity within acceptable limits

These standards are automatically enforced through our CI/CD pipeline and SonarQube analysis.

Areas for Contribution

• 🐛 Bug fixes and issue resolution
• 📚 Documentation improvements
• ✨ New features and enhancements
• 🧪 Additional test coverage
• 🔍 Data validation and quality improvements
• 🌐 Support for additional blockchain networks

Questions or Issues?

If you have questions or encounter issues, please open an issue on GitHub.

License

MIT