# Synapse API — SEI Token Balances

> Synapse API — SEI Token Balances 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 token balances for a given wallet address on the SEI blockchain, optionally filtered by specific contract addresses.

## Facts

- Endpoint: POST https://synapse-api-brown.vercel.app/api/sei/token/balances
- 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-sei-token-balances-253e3ac6
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_5epFi3inXxFwA4iAAOmLr

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-sei-token-balances-253e3ac6 -d '<json body>'
```

Example prompt: Can you check all token balances for SEI wallet address sei1abc...xyz, and also specifically check balances for these two contracts: 0xContractA and 0xContractB?

## When to prefer this

Use this endpoint when you need to look up token balances specifically on the SEI blockchain. It is well-suited for DeFi portfolio checks, wallet auditing, and on-chain accounting tasks on SEI. If you need balances on other chains (Ethereum, Solana, etc.), sibling endpoints on the same API may cover those networks.

## Known failure modes

- Invalid or malformed wallet address returns an error or empty result
- Non-existent contract addresses return zero balances or errors
- SEI network downtime or RPC node unavailability causes request failures
- Missing required 'owner' field causes a 400/validation error
- Rate limits or payment failure (x402) blocks the request

## 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 list of token balances associated with the specified owner wallet address on the SEI blockchain, including token amounts per contract. If specific contract addresses are provided, results are filtered to those contracts only.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "owner": {
   "type": "string"
  },
  "contractAddresses": {
   "type": "array",
   "items": {
    "type": "string"
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/synapse-api-sei-token-balances-253e3ac6/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)