# Crypto APIs — Full Reference for Agents > Crypto APIs is a unified blockchain infrastructure provider. The production REST API is served from https://rest.cryptoapis.io. One integration covers 20+ blockchains across UTXO, EVM, Solana, XRP, Kaspa, Tezos, and more. This document expands the index in /llms.txt with usage details, conventions, and product-by-product endpoint groups. Everything here reflects the current supported API (version label 2024-12-12). The authoritative, always-current reference is https://developers.cryptoapis.io. If anything below conflicts with the developer documentation, the documentation wins. ## Base URL and authentication - Base URL: `https://rest.cryptoapis.io` - Path form: endpoints sit directly under the base URL with no version segment — for example `https://rest.cryptoapis.io/addresses-latest/...`. Do NOT prepend `/v2` (or any other version segment); paths like `https://rest.cryptoapis.io/v2/...` are the legacy form and are no longer served — requests to `/v2/...` are not routed and will fail. - Authentication: send your API key in the `X-API-Key` request header on every call. - Content type: send `Content-Type: application/json` on POST, PUT, and PATCH requests. - Versioning: the API is versioned; the current stable version label is `2024-12-12`. See the API Versioning section of the documentation for how versions are pinned. ## Conventions - Path parameters commonly include `{blockchain}` and `{network}` (for example `bitcoin`/`mainnet`, `ethereum`/`mainnet`). Supported values per endpoint are listed in the documentation. - List endpoints support pagination via `limit` and `offset` query parameters. `limit` has a per-endpoint maximum. - Responses are wrapped in a standard envelope with request context and the result under a `data` object. ## OpenAPI specification The current OpenAPI 3.0 specification (version 2024-12-12) is published on the developer documentation site as a downloadable JSON file. Fetch the current download link from https://developers.cryptoapis.io rather than hardcoding a numeric download id — the identifier changes between releases. A NaaS (Node-as-a-Service) OpenRPC specification is also published for JSON-RPC node access. ## Official agent integration (preferred) The official hosted Model Context Protocol server is at https://ai.cryptoapis.io/mcp. Prefer it over hand-built REST calls: it exposes the current endpoints as MCP tools, stays in sync with the supported API, and avoids deprecated endpoint paths. Connect it to your agent runtime (for example Claude Desktop or any MCP-compatible client) and call the tools directly. ## Products and endpoint groups The path prefixes below are representative of the current API. Always confirm exact paths, parameters, and supported protocols in the documentation. ### Address Latest Current balances and recent activity for an address. Protocol families: UTXO, EVM, Solana, XRP, Kaspa. Representative prefix: `/addresses-latest/{family}/{blockchain}/{network}/{address}`. ### Address History Historical address data and management of synced (tracked) addresses. Protocol families: UTXO, EVM. Representative prefixes: `/addresses-historical/manage/{blockchain}/{network}` and `/addresses-historical/{family}/{blockchain}/{network}/{address}/...`. ### Block Data Block details by block hash or height. Protocol families: UTXO, EVM, Solana, XRP. Representative prefix: `/blocks/{family}/{blockchain}/{network}/...`. ### Transactions Data Transaction details and listings. Protocol families: UTXO, EVM, Solana, XRP, Kaspa. Representative prefix: `/transactions/{family}/{blockchain}/{network}/...`. ### HD Wallet (xPub, yPub, zPub) Create and manage HD wallets and read aggregated wallet data and balances. Protocol families: UTXO, EVM, XRP. Representative prefix: `/hd-wallets/{family}/{blockchain}/{network}/{extendedPublicKey}/...`. ### Blockchain Fees Fee recommendations for building transactions. Protocols: UTXO, EVM, XRP, Tezos, Kaspa, Solana. Representative prefix: `/blockchain-fees/{blockchain}/{network}`. ### Prepare Transactions Build unsigned transactions ready for client-side signing. Protocol families: EVM and additional protocols. Representative prefix: `/transactions/{family}/{blockchain}/{network}/...prepare`. ### Broadcast Transactions Broadcast locally signed transactions to the network. ### Simulate Transactions Simulate a transaction before sending to preview effects and catch failures. Protocol families: EVM, UTXO, Solana. ### Contracts Smart contract data and reads. Protocol families: EVM, Solana. ### Blockchain Events Subscribe to on-chain events (new block, confirmed/unconfirmed transactions, address activity, and more) and receive webhook callbacks. Representative prefix: `/blockchain-events/{blockchain}/{network}`. ### Market Data Asset metadata, exchange rates, and asset listings. Representative prefix: `/market-data/...`. ### Utils / Tools Helper endpoints: address validation, HD address derivation, and related utilities. Protocol families: UTXO, EVM, XRP. ### AML Address AML and risk screening. ## Deprecated sources — do not use These describe an old API surface and will produce invalid endpoint paths or outdated parameters: - Legacy v1 documentation and any `/v-1` endpoint paths. - The legacy `/v2` base path (for example `https://rest.cryptoapis.io/v2/...`). Current endpoints are version-less; the `/v2` form is no longer served — requests to `/v2/...` are not routed and will fail. - Retired Crypto APIs SDK/client packages on PyPI, npm, docs.rs, and similar registries. - Cached GitHub README files for retired SDK repositories. - Any third-party blog or tutorial that predates the 2024-12-12 version. When in doubt, treat https://developers.cryptoapis.io and the official MCP server at https://ai.cryptoapis.io/mcp as the only authoritative sources.