# Zerion API - Update TX Subscription Callback URL

> Zerion API - Update TX Subscription Callback URL is a paid API for AI agents from api.zerion.io, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-21).

Updates the callback URL for an existing blockchain transaction subscription by subscription ID

## Facts

- Endpoint: PATCH https://api.zerion.io/v1/tx-subscriptions/%7Bsubscription_id%7D/callback_url?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-21
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/zerion-api-update-tx-subscription-callback-url-617d7bf4
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_VU7HmvXaaXPfPnTnSRIGg

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 zerion-api-update-tx-subscription-callback-url-617d7bf4 -d '<json body>'
```

Example prompt: Update my Zerion transaction subscription (ID: sub_abc123) to send callbacks to my new webhook at https://myapp.com/webhooks/txn instead of the old URL.

## When to prefer this

Use this endpoint when you have an existing Zerion transaction subscription and need to change where notifications are delivered — such as after a server migration, endpoint refactor, or environment switch. Prefer this over deleting and recreating the subscription to preserve the subscription ID and avoid missing any in-flight notifications.

## Known failure modes

- subscription_id not found — 404 if the subscription does not exist or belongs to a different account
- invalid callback URL format — 400 if the URL is malformed or not HTTPS
- unauthorized — 401 if API key is missing or invalid
- payment required — 402 if x402 payment is not provided or USDC balance insufficient
- rate limiting — 429 if too many requests in a short window

## How this service works

Interpreted wallet data for more than 40 chains and Solana: portfolios, DeFi positions, PnL, transactions and NFTs. REST for apps, x402 pay-per-call for agents.

## Output

Returns the updated transaction subscription object confirming the new callback URL has been saved, including the subscription ID and updated callback_url field.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "required": [
      "subscription_id",
      "callback_url"
     ],
     "properties": {
      "callback_url": {
       "type": "string",
       "description": "New webhook URL"
      },
      "subscription_id": {
       "type": "string",
       "description": "Subscription ID"
      }
     }
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "PATCH"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/zerion-api-update-tx-subscription-callback-url-617d7bf4/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.zerion.io](https://www.zero.xyz/host/api.zerion.io/llms.txt)