# Synapse API — Plasma Transaction History

> Synapse API — Plasma Transaction History 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 using Alchemy's asset transfer API

## Facts

- Endpoint: POST https://synapse-api-brown.vercel.app/api/plasma/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-plasma-transaction-history-beade12e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_GHjuRhHvdddLRbZqgHGr2

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-plasma-transaction-history-beade12e -d '<json body>'
```

Example prompt: Can you pull the last 50 incoming transactions to 0xABCD...1234 on Ethereum, sorted newest-first, and include the token metadata for each transfer?

## When to prefer this

Use this endpoint when you need historical on-chain transaction data for a specific wallet or address pair, especially when you need to filter by category (ERC-20, ERC-721, ETH), paginate through large histories, or filter by block range. Prefer this over block explorers when you need structured, machine-readable output for agent processing.

## Known failure modes

- Invalid address format returns a 400 or empty result
- Unknown category string may silently filter all results
- pageKey expiration may cause pagination gaps
- fromBlock/toBlock mismatch or invalid hex values may cause errors
- maxCount exceeding API limits may return truncated results
- Network not supported by underlying Alchemy endpoint returns error

## 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 transfer records including transaction hashes, block numbers, from/to addresses, token amounts, contract addresses, asset categories, and optionally token metadata. A pageKey is included for fetching subsequent pages.

## 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-plasma-transaction-history-beade12e/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)