> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/bitcoin/bitcoin/llms.txt
> Use this file to discover all available pages before exploring further.

# REST Interface Overview

> Learn about Bitcoin Core's unauthenticated REST API, configuration, consistency guarantees, and limitations

## Introduction

Bitcoin Core provides an unauthenticated REST interface for querying blockchain data and network information. The REST API offers a simple HTTP-based alternative to the JSON-RPC interface for read-only operations.

## Enabling the REST Interface

The REST API is disabled by default. Enable it using the `-rest` configuration option:

```bash theme={null}
bitcoind -rest
```

Or in your `bitcoin.conf` file:

```
rest=1
```

## Network Configuration

The REST interface runs on the same port as the JSON-RPC interface:

| Network  | Port  |
| -------- | ----- |
| Mainnet  | 8332  |
| Testnet  | 18332 |
| Testnet4 | 48332 |
| Signet   | 38332 |
| Regtest  | 18443 |

## Authentication

The REST interface is **unauthenticated**. Unlike the JSON-RPC interface, REST endpoints do not require credentials. This makes the interface simpler to use but means you should be careful about exposing it to untrusted networks.

<Warning>
  **Security Consideration**: Since the REST interface is unauthenticated, avoid exposing it directly to the internet. Use firewall rules or a reverse proxy to restrict access to trusted clients only.
</Warning>

## Response Formats

Most REST endpoints support multiple output formats specified by the file extension:

| Format      | Extension | Content-Type               |
| ----------- | --------- | -------------------------- |
| Binary      | `.bin`    | `application/octet-stream` |
| Hexadecimal | `.hex`    | `text/plain`               |
| JSON        | `.json`   | `application/json`         |

Example:

```bash theme={null}
# Get block in JSON format
curl http://localhost:8332/rest/block/BLOCK_HASH.json

# Get block in hexadecimal format
curl http://localhost:8332/rest/block/BLOCK_HASH.hex

# Get block in binary format
curl http://localhost:8332/rest/block/BLOCK_HASH.bin
```

<Note>
  Some endpoints like `/rest/chaininfo` only support JSON output format.
</Note>

## Consistency Guarantees

The REST interface provides the same consistency guarantees as the JSON-RPC interface:

* All endpoints operate on a consistent view of the blockchain state
* Queries may return stale data during reorgs or when the node is catching up
* For critical applications, verify block confirmations independently

## Limitations and Warnings

### File Descriptor Exhaustion

<Warning>
  There is a known issue where too many simultaneous HTTP connections can cause the node to crash due to running out of available file descriptors.
</Warning>

To mitigate this:

1. **Increase system file descriptor limits**: Adjust your OS settings to allow more open files
2. **Rate limit connections**: If you control the clients, avoid opening hundreds of simultaneous connections
3. **Use connection pooling**: Reuse HTTP connections instead of creating new ones for each request

### Cross-Site Scripting (XSS) Risk

<Warning>
  **Browser Risk**: Running a web browser on the same machine as a REST-enabled Bitcoin node poses a privacy risk.
</Warning>

Malicious websites could potentially:

* Execute requests like `<script src="http://127.0.0.1:8332/rest/tx/TXID.json">`
* Read transaction and block data from your node
* Compromise your privacy by learning which transactions you're interested in

**Mitigation**: Do not browse untrusted websites on the same machine running a REST-enabled node.

### Transaction Index Requirement

Some endpoints require the transaction index to be enabled:

```bash theme={null}
bitcoind -txindex=1 -rest
```

<ParamField path="txindex" type="boolean" default="false">
  Enable the transaction index to query historical transactions via `/rest/tx/`
</ParamField>

Without `txindex=1`:

* `/rest/tx/` only searches the mempool
* Confirmed transactions cannot be queried

## Next Steps

* Explore [REST Endpoints](/api/rest-endpoints) for detailed endpoint documentation
* Learn about specific data formats for blocks, transactions, and UTXO queries
* See complete examples with curl commands