# 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 transaction history for blockchain addresses across 57+ networks, filtered by address, block range, category, and ordering.

## Facts

- Endpoint: POST https://synapse-api-brown.vercel.app/api/tempo/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-cd2806ba
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_XU8wI0Dzy4a_EXlJy8ODT

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-cd2806ba -d '<json body>'
```

Example prompt: Pull the full transaction history for wallet 0xABC...123 in descending order, include metadata, exclude zero-value transfers, and limit to 50 results — I want to see all incoming and outgoing transfers across ERC20 and external categories.

## When to prefer this

Choose this endpoint when you need filtered, paginated transaction history for one or more blockchain addresses with control over block range, transfer category, ordering, and metadata inclusion. Prefer it over generic block explorers when you need structured JSON output suitable for programmatic processing, and when pay-per-call pricing is acceptable for on-demand queries rather than a subscription.

## Known failure modes

- Invalid or missing address format returns 400 error
- Invalid block number format causes query failure
- Unsupported category type returns empty or error result
- pageKey expiration or invalidity causes pagination failure
- Network timeout for large block ranges
- Rate limiting or payment failure returns 402 if x402 payment not processed

## 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

Returns a paginated list of asset transfers/transactions matching the specified criteria, including transfer details such as block number, transaction hash, from/to addresses, asset type, value, and optionally full metadata. A pageKey is included when more results are available.

## 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-cd2806ba/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)