# Synapse API — Avalanche Transaction History

> Synapse API — Avalanche 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 2026-09-14).

Retrieves paginated transaction history for addresses on the Avalanche blockchain network

## Facts

- Endpoint: POST https://synapse-api-brown.vercel.app/api/avalanche/tx/history
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/synapse-api-avalanche-transaction-history-a4eed308
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_I6Y_5aMu3c60BP0Y8e75d

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-avalanche-transaction-history-a4eed308 -d '<json body>'
```

Example prompt: Pull me the last 25 transactions for Avalanche address 0xAbC...123, sorted newest first, and include token metadata — filter out any zero-value transfers.

## When to prefer this

Use this endpoint when you need on-chain transaction history specifically for the Avalanche network with flexible filtering by address, block range, asset category, and sort order. Prefer it over generic blockchain explorers when you need programmatic, paginated access with metadata in a structured JSON format and are willing to pay per call via USDC.

## Known failure modes

- Invalid or malformed address returns a 400 error
- Block range too large may result in timeout or truncated results
- Invalid category values cause request rejection
- Missing both fromAddress and toAddress may return an error or empty result
- pageKey from a different query context causes unpredictable pagination behavior
- Rate limiting or payment failure returns 402 or 429 status

## 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 on the Avalanche network matching the specified filters, including transaction hashes, block numbers, sender/recipient addresses, asset amounts, and optionally token metadata. A pageKey is provided 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-avalanche-transaction-history-a4eed308/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)