canonical: https://jentic.com/apis/chain49.com/chain49

# Chain49 API

Chain49 is an extended Trezor/Blockbook-style multi-chain blockchain data API that exposes block, transaction, address, xpub, UTXO, NFT, and JSON-RPC endpoints across more than 10 chains out of the box and 50+ available on request. The API is consumed either directly at api.chain49.com with a Chain49 X-API-Key or through the RapidAPI marketplace using the matching X-RapidAPI headers, and supports both read queries and transaction broadcast.

## For AI agents

Read blocks, transactions, addresses, xpubs, UTXOs, NFTs, and mempool data and broadcast transactions across 10+ blockchains via Chain49's hosted Blockbook-compatible API.

## Scope

Does not custody private keys, sign transactions, or run smart-contract simulation - use for hosted blockchain data reads and signed-transaction broadcast only.

## Capabilities

- List the blockchains Chain49 currently exposes and read each chain's summary info
- Retrieve a block by hash or height including raw block data on supported chains
- Look up a transaction by id in either Blockbook-normalised or backend-native form
- Read address state including balance, transactions, and history across supported chains
- Resolve an xpub into its derived addresses, balances, and UTXO set
- Broadcast a signed transaction either via GET with hex in the URL or POST
- Fetch fee estimates, mempool contents, NFT metadata, and ticker price data per chain

## Use cases

### Multi-Chain Wallet Backend

Power a wallet that supports multiple chains from a single API surface. The {blockchain} path parameter lets the same `/v2/address`, `/v2/xpub`, and `/v2/utxo` endpoints serve Bitcoin, Litecoin, Dogecoin, and other supported chains so the wallet does not need a per-chain integration. POST /{blockchain}/v2/sendtx broadcasts a signed transaction once the wallet has signed locally.

Example prompt: Call GET /{blockchain}/v2/xpub/{xpub} for the user's xpub on each supported chain and aggregate the total balance and address list

### On-Chain Data Pipeline

Feed an analytics or indexer pipeline with block-level data without operating per-chain nodes. GET /{blockchain}/v2/block/{blockHashOrHeight} returns parsed block contents and GET /{blockchain}/v2/rawblock/{blockHashOrHeight} returns the raw block bytes for custom decoders. GET /{blockchain}/v2/mempool exposes pending transactions for real-time monitoring.

Example prompt: Call GET /{blockchain}/v2/block-index/{blockHeight} to resolve a height to a hash, then GET /{blockchain}/v2/rawblock/{blockHashOrHeight} and persist the result

### Transaction Broadcast Service

Run a custodial or semi-custodial signer that builds and signs transactions in-house and uses Chain49 only for broadcast and confirmation tracking. POST /{blockchain}/v2/sendtx submits a signed hex, then GET /{blockchain}/v2/tx/{txId} polls the parsed transaction state, and GET /{blockchain}/v2/estimatefee/{confirmationTarget} feeds a dynamic fee policy.

Example prompt: Call POST /{blockchain}/v2/sendtx with the signed hex, then poll GET /{blockchain}/v2/tx/{txId} until the confirmations field exceeds 1

### AI Agent Multi-Chain Lookup via Jentic

An agent receives a request like 'tell me the BTC and LTC balances at this xpub and the latest fee estimate for each chain'. Through Jentic, the agent searches for an xpub-balance operation and a fee-estimate operation, loads each input schema, and calls `/v2/xpub` and `/v2/estimatefee` with credentials drawn from your Jentic One instance. The agent answers across both chains without per-chain wiring.

Example prompt: Use Jentic to search 'get xpub balance' and execute it for chain 'bitcoin' and chain 'litecoin', then search 'estimate transaction fee' for both

## Key endpoints

| Method | Path | Description |
| --- | --- | --- |
| GET | `/` | List supported blockchains |
| GET | `/{blockchain}/v2/address/{address}` | Read address state and transactions |
| GET | `/{blockchain}/v2/xpub/{xpub}` | Resolve xpub to derived addresses and balances |
| GET | `/{blockchain}/v2/utxo/{addressOrXpub}` | List unspent outputs for an address or xpub |
| GET | `/{blockchain}/v2/tx/{txId}` | Read a transaction by id |
| POST | `/{blockchain}/v2/sendtx` | Broadcast a signed transaction |
| GET | `/{blockchain}/v2/estimatefee/{confirmationTarget}` | Estimate fee for a confirmation target |
| POST | `/{blockchain}/rpc` | Pass-through JSON-RPC endpoint |

## Key resources

- **Blockchains** — List supported chains and read per-chain summary info
- **Blocks** — Resolve heights to hashes, fetch parsed and raw block data
- **Transactions** — Read transactions by id in normalised or backend form, broadcast signed transactions, and inspect the mempool
- **Addresses and Xpubs** — Read address state, xpub-derived address sets, UTXOs, and historical balances
- **Fees and Tickers** — Estimate fees per confirmation target and read ticker price data
- **NFTs** — Read NFT metadata by contract and token id on supported chains
- **JSON-RPC** — Pass through JSON-RPC calls to underlying chain backends

## Why Jentic

- **Setup:** Wiring the Chain49 API by hand means handling its X-API-Key header, choosing between the direct api.chain49.com host and the RapidAPI host, and threading the {blockchain} path segment through every call yourself. Through Jentic you install once, import the Chain49 API from the API Directory, store the key once, and your agent calls it.
- **Permission scoping:** Chain49 puts the blockchain and address in the URL path for operations like /{blockchain}/v2/address/{address}, so a rule can pin your agent to reads for one address on one chain. You choose the operations it may call, so broadcasting a signed transaction is not included unless you add it.
- **Credential handling:** Your Chain49 API key is stored once, encrypted, by your own Jentic One instance and injected at execution time. It never enters the agent's prompt, logs, or context.
- **Discovery method:** Agents search Jentic by intent such as 'get an address balance' or 'broadcast a signed transaction', and Jentic returns the matching Chain49 operation with its input schema so the agent calls the right endpoint with the correct blockchain segment without browsing the reference docs.

## Related APIs

- **Alchemy API** — EVM-focused blockchain infrastructure API with deep Ethereum tooling
- **Tatum API** — Multi-chain blockchain and wallet API across BTC, EVM, and many other chains
- **CoinGecko API** — Crypto asset price and market cap data across thousands of coins

## FAQ

### What authentication does the Chain49 API use?

Chain49 supports two header-based modes. Direct calls to api.chain49.com use the X-API-Key header with a Chain49-issued key. Calls routed through RapidAPI use X-RapidAPI-Key plus X-RapidAPI-Host. Through Jentic, the appropriate keys live in your Jentic One instance and are added at execution time so they never enter the agent's prompt or context window.

### Which chains does the Chain49 API support?

The API exposes more than 10 chains out of the box and lists 50+ available on request. The exact set is dynamic - call GET / to read the current list of blockchain identifiers, then use those values as the {blockchain} path parameter on every other endpoint.

### Can I broadcast a signed transaction with the Chain49 API?

Yes. POST /{blockchain}/v2/sendtx accepts a signed transaction hex in the body, and GET /{blockchain}/v2/sendtx/{hex} accepts the hex inline in the URL for compatibility with simple clients. Pair with GET /{blockchain}/v2/tx/{txId} to poll for confirmations.

### What are the rate limits for the Chain49 API?

Limits are tied to your plan and to the channel you call through; RapidAPI plans publish their own quotas while direct keys are throttled per Chain49's commercial tiers. Watch for 429 responses with Retry-After headers and set client concurrency to match the lower of the two ceilings.

### How do I read an xpub balance with the Chain49 API through Jentic?

Search Jentic for 'get an xpub balance', load the operation backed by GET /{blockchain}/v2/xpub/{xpub}, and execute it with the chain id and xpub. Jentic injects the X-API-Key header so the agent receives the typed xpub response with derived address counts and totals.

### Does the Chain49 API support NFT metadata lookups?

Yes, on supported EVM chains. GET /{blockchain}/v2/nft/{nftContract}/{nftTokenId} returns the metadata Chain49 has indexed for that contract and token id, which is useful for wallet UIs that display owned NFTs without integrating a separate indexer.

### Can I limit what my agent is allowed to do with the Chain49 API?

Yes. Because you run Jentic One yourself, you decide which Chain49 operations your agent may call and which stored key it uses. Chain49 puts the chain and address directly in the path, as in GET /{blockchain}/v2/address/{address}, so your own rules can pin the agent to read-only lookups for a single address on a single chain. A write operation like POST /{blockchain}/v2/sendtx that broadcasts a signed transaction stays off limits unless you explicitly grant it.