# Synapse API — Blockchain Transaction History Lookup

> Synapse API — Blockchain Transaction History Lookup is a paid API for AI agents from synapse-api-brown.vercel.app, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-13).

Retrieves paginated historical transactions for a blockchain address across 57+ networks, filtered by block range, category, and address

## Facts

- Endpoint: POST https://synapse-api-brown.vercel.app/api/stable/tx/history
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/synapse-api-blockchain-transaction-history-lookup-860b4db9
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_FkVi3dD9Whcbii1ZrLWS3

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability synapse-api-blockchain-transaction-history-lookup-860b4db9 -d '<json body>'
```

Example prompt: Pull the last 50 transactions sent from wallet 0xAbC...123, sorted newest first, including metadata, and skip any zero-value transfers.

## When to prefer this

Use this endpoint when you need historical on-chain transaction data for a specific wallet or address across a wide range of blockchain networks, especially when you need pagination, block-range scoping, or category filtering. Prefer this over generic blockchain explorers when you need machine-readable structured output for agent workflows or when paying per-call via x402 micropayments is acceptable.

## Known failure modes

- Invalid address format returns an error
- Block range out of bounds or non-existent returns empty results
- Invalid category enum value causes request rejection
- Missing required address fields may return unfiltered or empty results
- pageKey expiry causes pagination to restart
- Network timeout on large block ranges

## How this service works

High-speed API suite for AI processing, web scraping, and smart data utilities across 57+ blockchain networks. Pay-per-call via x402.

## Output

A paginated list of historical blockchain transactions matching the query filters, optionally including metadata such as token names, contract addresses, and asset values. Results can be ordered ascending or descending by block, scoped by block range, filtered by sender/receiver address and transaction category, and paginated using a pageKey for subsequent requests.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "order": {
   "enum": [
    "asc",
    "desc"
   ],
   "type": "string"
  },
  "pageKey": {
   "type": "string"
  },
  "toBlock": {
   "type": "string"
  },
  "category": {
   "type": "array",
   "items": {
    "type": "string"
   }
  },
  "maxCount": {
   "type": "number"
  },
  "fromBlock": {
   "type": "string"
  },
  "toAddress": {
   "type": "string"
  },
  "fromAddress": {
   "type": "string"
  },
  "withMetadata": {
   "type": "boolean"
  },
  "excludeZeroValue": {
   "type": "boolean"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/synapse-api-blockchain-transaction-history-lookup-860b4db9/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from synapse-api-brown.vercel.app](https://www.zero.xyz/host/synapse-api-brown.vercel.app/llms.txt)