Authentication

No Authentication Required

The Mempool API is designed to be publicly accessible and does not require authentication for standard read operations. This makes it easy to integrate Bitcoin data into your applications without managing API keys or tokens.

All public endpoints are available without any authentication headers or API keys.

Public Endpoints

The following categories of endpoints are freely accessible:

Read Operations

All GET endpoints are publicly accessible without authentication:

Transactions - Query transaction data, status, and outspends
Addresses - Get address information, balances, and transaction history
Blocks - Retrieve block data and headers
Mining - Access mining statistics and pool information
Fees - Get real-time fee recommendations
Mempool - View current mempool state
Lightning Network - Query Lightning Network data
Statistics - Access historical statistics

# Simple GET request - no authentication needed
curl https://mempool.space/api/v1/blocks/tip/height

# Returns: 825000

Write Operations

Transaction Broadcasting

The API supports broadcasting transactions to the Bitcoin network without authentication:

# Broadcast a raw transaction (no auth required)
curl -X POST \
  https://mempool.space/api/v1/tx \
  -H 'Content-Type: text/plain' \
  -d '0200000001...'

# Returns: transaction_id

Transaction Size LimitsTransactions must not exceed the maximum size limit. The backend configuration sets MAX_PUSH_TX_SIZE_WEIGHT to control transaction weight limits.

Package Submission

For advanced users, the API supports package submission (Bitcoin Core 28+):

POST /txs/package

curl -X POST \
  https://mempool.space/api/v1/txs/package \
  -H 'Content-Type: application/json' \
  -d '[
    "0200000001...",
    "0200000001..."
  ]'

Backend Requirements

Backend Types

The Mempool backend can be configured with different Bitcoin data sources:

Backend	Description	Address Lookups
esplora	Mempool/electrs backend	✅ Supported
electrum	Electrum server backend	✅ Supported
none	Direct Bitcoin Core only	❌ Not supported

When the backend is set to none (Bitcoin Core only), certain endpoints like address lookups return a 405 Method Not Allowed error.

Endpoint Availability

Some endpoints require specific backend configurations:

Address Endpoints (Requires esplora or electrum)

Example Error

curl https://mempool.space/api/v1/address/1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa

# With backend=none, returns:
{
  "error": "Address lookups cannot be used with bitcoind as backend."
}

Summary Endpoints (Requires esplora)

Esplora Only

# These endpoints require mempool/electrs backend
GET /address/{address}/txs/summary
GET /scripthash/{scripthash}/txs/summary

Service-Specific Endpoints

Certain advanced features require additional service configuration:

Acceleration Services

Limited AvailabilityAcceleration endpoints are only available:

When MEMPOOL_SERVICES.ACCELERATIONS is enabled
On Bitcoin mainnet (not available on testnet, signet, liquid, etc.)

Acceleration Request

POST /api/v1/acceleration/request/{txid}

# Returns 400 if not configured:
{
  "error": "Acceleration data is not available."
}

Historical Prices

Price data is only available on mainnet:

Price Endpoint

GET /api/v1/historical-price?timestamp=1234567890&currency=USD

# On testnet returns:
{
  "error": "Prices are not available on testnets."
}

CORS Support

The Mempool API includes full Cross-Origin Resource Sharing (CORS) support:

Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET, POST, PUT, DELETE, OPTIONS
Access-Control-Allow-Headers: Accept,Authorization,Cache-Control,Content-Type,DNT,If-Modified-Since,Keep-Alive,Origin,User-Agent,X-Requested-With
Access-Control-Expose-Headers: X-Total-Count,X-Mempool-Auth

All origins are allowed (*), making the API accessible from any web application without CORS issues.

Request Headers

No special headers are required for most requests:

Standard Request

curl -X GET \
  https://mempool.space/api/v1/blocks/tip/height

For POST requests with JSON data:

JSON POST Request

curl -X POST \
  https://mempool.space/api/v1/prevouts \
  -H 'Content-Type: application/json' \
  -d '[{"txid":"abc...","vout":0}]'

For broadcasting transactions:

Transaction Broadcast

curl -X POST \
  https://mempool.space/api/v1/tx \
  -H 'Content-Type: text/plain' \
  -d '0200000001...'

Self-Hosted API Access

If you’re running your own Mempool instance:

Configure Your Backend

Set up MEMPOOL.BACKEND in your configuration:

esplora - Full functionality including address lookups
electrum - Full functionality via Electrum server
none - Limited to Bitcoin Core RPC capabilities

Set API URL Prefix

The default API prefix is /api/v1/ and can be configured via MEMPOOL.API_URL_PREFIX.

Configure Services

Enable optional services like accelerations in MEMPOOL_SERVICES configuration.

Access Your API

Your API will be available at: http://your-domain.com/api/v1/

Security Considerations

No Sensitive Operations

The API does not expose any sensitive operations that would require authentication:

✅ Read-only data access - Blockchain and mempool data is public
✅ Transaction broadcasting - Standard Bitcoin network operation
✅ No private data - API does not store user-specific information
✅ No write access - Cannot modify blockchain or database state

Input Validation

All inputs are validated using regex patterns:

Validation Patterns

// Transaction IDs
TXID_REGEX = /^[a-f0-9]{64}$/i

// Block hashes
BLOCK_HASH_REGEX = /^[a-f0-9]{64}$/i

// Addresses
ADDRESS_REGEX = /^[a-z0-9]{2,120}$/i

// Script hashes
SCRIPT_HASH_REGEX = /^([a-f0-9]{2})+$/i

Invalid inputs return 400 Bad Request or 501 Not Implemented with descriptive error messages.

Rate Limiting

While no authentication is required, the API implements rate limiting to ensure fair usage. See the Rate Limits documentation for details.

Best Practices

Use Appropriate HTTP Methods

Use GET for reading data
Use POST for broadcasting transactions and submitting data
Handle OPTIONS requests for CORS preflight

Handle Errors Gracefully

Check HTTP status codes and parse error messages from the JSON response:

fetch('https://mempool.space/api/v1/tx/' + txid)
  .then(response => {
    if (!response.ok) {
      return response.json().then(err => {
        throw new Error(err.error || 'API Error');
      });
    }
    return response.json();
  })
  .catch(error => console.error('Error:', error));

Respect Backend Limitations

Check which backend your target instance is using and adjust your application accordingly. Some features require specific backends.

Cache Responses

Many endpoints include cache headers. Respect these to reduce load:

Expires: Thu, 02 Mar 2026 22:30:00 GMT
Cache-Control: public
Pragma: public

Overview

Blockchain

Mempool

Mining

Lightning Network

Services

No Authentication Required

Public Endpoints

Read Operations

Write Operations

Transaction Broadcasting

Package Submission

Backend Requirements

Backend Types

Endpoint Availability

Address Endpoints (Requires esplora or electrum)

Summary Endpoints (Requires esplora)

Service-Specific Endpoints

Acceleration Services

Historical Prices

CORS Support

Request Headers

Self-Hosted API Access

Security Considerations

No Sensitive Operations

Input Validation

Rate Limiting

Best Practices

Next Steps

Rate Limits

API Reference

Build docs developers (and LLMs) love

Overview

Blockchain

Mempool

Mining

Lightning Network

Services

​No Authentication Required

​Public Endpoints

​Read Operations

​Write Operations

​Transaction Broadcasting

​Package Submission

​Backend Requirements

​Backend Types

​Endpoint Availability

​Address Endpoints (Requires esplora or electrum)

​Summary Endpoints (Requires esplora)

​Service-Specific Endpoints

​Acceleration Services

​Historical Prices

​CORS Support

​Request Headers

​Self-Hosted API Access

​Security Considerations

​No Sensitive Operations

​Input Validation

​Rate Limiting

​Best Practices

​Next Steps

Rate Limits

API Reference

Build docs developers (and LLMs) love

No Authentication Required

Public Endpoints

Read Operations

Write Operations

Transaction Broadcasting

Package Submission

Backend Requirements

Backend Types

Endpoint Availability

Address Endpoints (Requires esplora or electrum)

Summary Endpoints (Requires esplora)

Service-Specific Endpoints

Acceleration Services

Historical Prices

CORS Support

Request Headers

Self-Hosted API Access

Security Considerations

No Sensitive Operations

Input Validation

Rate Limiting

Best Practices

Next Steps