# Synapse API — Base Blockchain Transaction History

> Synapse API — Base Blockchain 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 2026-09-15).

Retrieves paginated transaction history for addresses on the Base blockchain network, with filtering by block range, category, and address.

## Facts

- Endpoint: POST https://synapse-api-brown.vercel.app/api/base/tx/history
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/synapse-api-base-blockchain-transaction-history-cdfce843
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_MGkMYT7iSRaLBu9kCxIgl

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-base-blockchain-transaction-history-cdfce843 -d '<json body>'
```

Example prompt: Pull me the last 25 transactions for Base address 0xABC123... going from newest to oldest, including metadata, and skip any zero-value transfers.

## When to prefer this

Choose this endpoint when you need on-chain transaction history specifically for the Base (Coinbase L2) network, with flexible filtering by address, block range, transaction category, and sort order. Prefer it over generic block explorers when you need programmatic, paginated, machine-readable output with metadata for agent workflows or wallet audits.

## Known failure modes

- Invalid or malformed address returns an error
- Block range too large may time out or return partial results
- Invalid category enum value causes a 400 error
- Expired or invalid pageKey breaks pagination
- Rate limiting or payment failure returns 402

## 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 transactions on the Base blockchain matching the specified filters, including transaction hashes, block numbers, from/to addresses, values, and optionally full metadata. A pageKey is returned when more results are available for subsequent calls.

## 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-base-blockchain-transaction-history-cdfce843/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)