Zero Auth

Quick Reference

WhatZero-value card validation

WhyConfirm a card is active without moving money

DifficultyBeginner

PrerequisitesAuthentication → Wallet

Zero-auth sends a non-monetary pre-authorization to the card network, confirming the card exists, is active, and can accept charges — without moving any funds.

Why zero-auth

Use case	Benefit
Subscription setup	Validate the card before the first billing cycle begins
Card-on-file	Confirm a stored card is still valid before a future charge
Fraud pre-check	Detect stolen or blocked cards at onboarding, not at checkout
Onboarding	Verify payment credentials during account creation

Endpoint

POST https://sandbox.api.a55.tech/api/v1/bank/wallet/zeroauth/

Postman: Import the A55 API Collection to test this endpoint interactively.

Request fields

Field	Type	Required	Description
`wallet_uuid`	string	Yes	Wallet identifier
`holder_name`	string	Yes	Name as printed on the card
`card_number`	string	Yes	Full PAN
`expiry_month`	string	Yes	Two-digit month
`expiry_year`	string	Yes	Four-digit year
`cvv`	string	Yes	Card verification value
`brand`	string	No	Card brand (auto-detected if omitted)

cURL
Python
JavaScript

curl -X POST https://sandbox.api.a55.tech/api/v1/bank/wallet/zeroauth/ \
  -H "Authorization: Bearer $TOKEN" -H "Content-Type: application/json" \
  -d '{"wallet_uuid":"wal_abc123","holder_name":"Jane Doe","card_number":"4111111111111111","expiry_month":"12","expiry_year":"2027","cvv":"123"}'

resp = requests.post("https://sandbox.api.a55.tech/api/v1/bank/wallet/zeroauth/",
    headers={"Authorization": f"Bearer {token}"},
    json={"wallet_uuid": "wal_abc123", "holder_name": "Jane Doe",
          "card_number": "4111111111111111", "expiry_month": "12",
          "expiry_year": "2027", "cvv": "123"})

const resp = await fetch("https://sandbox.api.a55.tech/api/v1/bank/wallet/zeroauth/", {
  method: "POST",
  headers: { Authorization: `Bearer ${token}`, "Content-Type": "application/json" },
  body: JSON.stringify({ wallet_uuid: "wal_abc123", holder_name: "Jane Doe",
    card_number: "4111111111111111", expiry_month: "12", expiry_year: "2027", cvv: "123" }),
});

Response examples

Valid card:

{ "status": "confirmed", "response_code": "00", "message": "Card is valid and active" }

Invalid card:

{ "status": "declined", "response_code": "14", "message": "Invalid card number" }

Zero-auth flow

Response codes

Code	Description	Action
`00`	Approved	Card is valid — proceed
`05`	Do not honor	Contact cardholder — issuer declined without specific reason
`14`	Invalid card number	Check for typos in the PAN
`51`	Insufficient funds	Not relevant for zero-auth — treat as valid card
`54`	Expired card	Request updated card details
`57`	Transaction not permitted	Card type does not support this operation
`62`	Restricted card	Card is flagged — do not proceed
`63`	Security violation	CVV mismatch — ask cardholder to re-enter
`76`	Invalid account	Account closed or non-existent
`79`	Lifecycle decline	Card was recently reissued — request new details
`N7`	CVV mismatch	Verify the CVV with the cardholder
`91`	Issuer unavailable	Retry after 30 seconds
`96`	System malfunction	Retry with exponential backoff
`389`	Fraud suspicion	Do not retry — flag for manual review
`500`	A55 internal error	Retry or contact support

Pair with tokenization

Combine zero-auth with tokenization: validate the card first, then tokenize it in the same flow. This ensures you only store tokens for cards that are confirmed active.

Sandbox testing

Simulate approvals and declines without real issuer calls using Test Cards. The same last-digit rules apply to zero-auth, tokenization, and charges.

Card Tokenization →Store the validated card as a secure token Subscriptions →Set up recurring billing after validation Anti-Fraud →Enrich charges with device and behavioral signals

Quick Reference

Why zero-auth​

Endpoint​

Request fields​

Response examples​

Zero-auth flow​

Response codes​