Metadata

Attach your own data to a payment with metadata: up to 20 keys of up to 40 characters, with string values up to 500 characters. Keys use only letters, digits, _, . and -.

• PATCH /payments/{id} merges by key. Set a key to an empty string or null to remove it, or send "metadata": null to clear them all.
• Filter lists by it, such as GET /payments?metadata[order_id]=1042.
• It comes back on the payment and in every event about it, so your webhook handler has what it needs.