Credit Card Validator & Test Number Generator
Validate credit card numbers with the Luhn algorithm and generate synthetic, Luhn-valid test PANs for any major card brand — all in your browser, with no data sent anywhere.
Card Preview
Click on the card number line above to type — the preview updates live as you enter digits.
Validation Results
Enter a credit card number to validate
Test Card Numbers
Note: These are test numbers for validation purposes only. Never use real credit card numbers for testing.
About the Luhn Algorithm
The Luhn algorithm (also known as the "modulus 10" algorithm) is a checksum formula used to validate credit card numbers and detect simple errors in typing.
How it works:
- Starting from the rightmost digit, double every second digit
- If doubling results in a number > 9, subtract 9
- Sum all the digits
- If the total is divisible by 10, the number is valid
About Credit Card Validator & Test Number Generator
A privacy-first credit-card workbench that does two things: (1) validates a card number with the industry-standard Luhn (mod-10) checksum and reports the detected brand and any issuer-region cues, and (2) generates synthetic, Luhn-valid test PANs for any of 10 supported brands — Visa, MasterCard, American Express, Discover, Diners Club, JCB, UnionPay, Maestro, Mir, and RuPay. Both modes run entirely in your browser; no card number is ever transmitted, logged, or persisted.
Why use a Credit Card Validator & Test Number Generator?
Validate to catch typos before a payment ever reaches your gateway, show the right brand logo, and apply the right CVC/length rules client-side. Generate when you need fresh test PANs for QA suites, sandbox environments, fraud-screening rules, or end-to-end test fixtures — without copy-pasting from a stale gist or, worse, calling out to a third-party 'card generator' service that you can't audit. The combined tool gives you a complete, client-side payment-card sandbox.
Who is it for?
Built for e-commerce and fintech developers wiring up payment forms, QA engineers writing Cypress / Playwright suites against checkout flows, fraud analysts triaging declined transactions, sandbox / staging-env operators seeding test data, and security/compliance teams who need tools that don't phone home with PANs. Also useful for students learning how the Luhn algorithm and ISO/IEC 7812 issuer identification numbers actually work.
How to use the tool
Pick a mode at the top of the left panel: Validate (check an existing number) or Generate (produce synthetic test numbers)
Validate mode: type or paste a card number into the card-preview input — the tool auto-formats as you type and the right panel shows brand, length, Luhn status, errors, and warnings
Generate mode: pick a brand, choose how many test PANs you want (1–25), click Generate — the right panel lists Luhn-valid synthetic numbers, each with a one-click Copy button so you can drop them straight into your test fixtures or sandbox environment
Use the test-card list below the tool (in Validate mode) for known-good and known-bad samples covering every supported brand
All processing is client-side — verify in your DevTools network tab: typing or generating produces zero requests
Key Features
Validate mode — Luhn (mod-10) check
Runs the same checksum algorithm used by every payment processor — catches typos, transposed digits, and most random-input attempts before the card is ever sent to a gateway.
Generate mode — Luhn-valid test PANs
Produce one or many synthetic test PANs for any supported brand. Each generated number passes Luhn by construction, uses a real-world brand prefix, and matches the brand's expected length and format — perfect for seeding test fixtures.
10 card brands recognised
Visa, MasterCard, American Express, Discover, Diners Club, JCB, UnionPay (China), Maestro (legacy debit), Mir (Russia), and RuPay (India) — covering virtually every major global network. Both validation and generation work for all 10.
Issuer-region inference (where meaningful)
Network-bound brands get a region badge (e.g. UnionPay → China, Mir → Russia, RuPay → India). Truly global networks (Visa, MasterCard, Amex, Diners, Maestro) intentionally show no region — because their prefix tells you nothing about the issuing country.
Brand-aware formatting
Auto-formats the input as you type — 4-4-4-4 for most cards, 4-6-5 for American Express, 4-6-4 for Diners Club — matching what users see on their physical card.
Per-brand length and CVC rules
Validates the digit count against the brand's allowed lengths (e.g. Amex 15, Visa 13/16/19) and shows the expected CVC length (3 for most, 4 for Amex).
100% client-side
Both validation and generation run entirely in your browser. No card number is ever transmitted, logged, or persisted — verifiable in your DevTools network tab (zero requests for either operation).
One-click copy on every generated number
Each generated PAN has its own Copy button — copy any number with a single click, then paste straight into your test fixture, Cypress spec, or sandbox payment form.
Common Use Cases
Seeding QA / E2E test data
Scenario: You're populating a Cypress / Playwright suite with a fresh batch of valid-format card numbers across multiple brands every test run.
✓ Generate 10 brand-mixed Luhn-valid PANs in one click, copy them straight into your fixtures — no risk of stale gist links breaking your tests months later.
E-commerce checkout form validation
Scenario: You're building a checkout flow and need client-side validation before posting the card to your payment processor.
✓ Catch typos early, show the right brand logo, and avoid a round-trip-then-decline that costs you the sale.
Negative-path testing
Scenario: You need to confirm your checkout form handles invalid card numbers gracefully — wrong checksum, wrong length, unknown brand, leading zero.
✓ The built-in test-card list (in Validate mode) includes deliberately invalid samples covering each failure mode — copy them into your test cases for negative coverage.
Fraud triage
Scenario: You're investigating a declined or charged-back transaction and want a quick read on the issuer brand and likely region.
✓ Paste the BIN-only portion (first 6 digits) and immediately see the brand and region without exposing the PAN to a third-party BIN service.
Payment-integration learning
Scenario: You're new to PCI / payments and want to understand how the Luhn algorithm and BIN ranges actually work.
✓ Try the test cards, watch the Luhn status flip when you change a single digit, and read the inline algorithm explanation.
Internal tooling
Scenario: Your support / ops team needs a quick validator for cards customers read out over the phone, without the privacy risk of a hosted SaaS tool.
✓ Self-contained static page — works offline once loaded, never transmits PANs, suitable for use behind a VPN or air-gapped network.
10 card brands; ISO/IEC 7812-compliant Luhn for both validate and generate
100% client-side — card numbers never leave your device
Static site — no backend dependency
Frequently Asked Questions
Are the generated numbers real, usable cards?
No. They are synthetic test PANs — they pass the Luhn checksum and use a real-world brand prefix, but no bank ever issued them. They will be recognised as 'well-formed' by your client-side validation and by sandbox payment processors that only check format, but they will be declined the moment they hit a real card network. Use them strictly for development, QA, and educational purposes.
What's the difference between Validate mode and Generate mode?
Validate takes an existing card number and tells you whether it's well-formed (passes Luhn, matches a known brand pattern, has the right length). Generate does the inverse — you pick a brand and the tool produces fresh, Luhn-valid synthetic numbers in that brand's format. Both modes run client-side; switching between them just toggles the UI.
Can I generate cards for a specific bank or country?
No. The generator works at the brand-network level (Visa / MasterCard / Mir / etc.) using publicly-documented prefix ranges, not at the bank level. True bank-specific BIN ranges aren't in the public domain — getting them requires a paid commercial BIN data feed, which would mean sending the PAN to a third party and breaking this tool's privacy guarantee.
Does this tool send my card number anywhere?
No. All validation runs entirely in your browser — Luhn checksum, brand detection, length rules, and region inference. There are no API calls, no analytics events with the card number, and no logs. You can verify this in your browser's DevTools network tab — typing or pasting a card produces zero network requests.
Is a card 'valid' according to this tool actually a real, usable card?
No. Luhn validation only proves the number is mathematically well-formed — it does not prove the card was ever issued, is currently active, or has funds. Only the issuing bank can confirm that. Treat 'valid' here as 'not obviously a typo'.
What is the Luhn algorithm and why does it matter?
The Luhn algorithm (mod-10) is a checksum invented in 1954 and used by every payment network. It catches every single-digit typo and almost every transposition of adjacent digits. Running it client-side stops bad input before it ever hits your payment processor, saving on per-attempt fees and improving conversion.
Why do I see 'region' instead of 'issuing bank'?
True bank-level BIN lookup requires either a multi-megabyte data table (which goes stale within months) or an external API call (which sends part of the PAN to a third party — a privacy compromise). This tool stays client-side and reports the region that's structurally implied by the brand prefix (UnionPay → CN, RuPay → IN, Mir → RU, etc.) rather than pretending to do a full lookup.
Which card brands are supported?
Visa (4), MasterCard (51-55, 2221-2720), American Express (34, 37), Discover (6011, 65), Diners Club (300-305, 36, 38), JCB (35), UnionPay (62), Maestro (5018/5020/5038/5893/6304/6759/676x), Mir (2200-2204), and RuPay (508x/6069/607x/6521-6522).
Why does the test card I pasted show as 'invalid'?
Common causes: a digit was dropped or added during paste; the card belongs to a brand the tool doesn't recognise (rare — let us know which); or the test number was deliberately constructed to fail Luhn (some payment processors publish 'invalid by design' samples for negative-path testing).
Does the validator check the expiry date or CVC?
No. It validates the PAN only. It will tell you the expected CVC length for the detected brand (3 digits for most, 4 for Amex), but it does not validate or store the CVC or expiry — those are out of scope for a Luhn / brand validator.
Can I use real card numbers here?
Technically yes — nothing is transmitted — but it's still bad practice to type real cards into any tool you didn't build yourself. Use the included test PANs (or your processor's published sandbox cards) for development. Use real cards only against the actual payment form on the merchant site.
Technical Specifications
Supported Formats
- ✓Visa — 13, 16, or 19 digits, prefix 4
- ✓MasterCard — 16 digits, prefix 51-55 or 2221-2720
- ✓American Express — 15 digits, prefix 34 or 37, 4-digit CID
- ✓Discover — 16 digits, prefix 6011 or 65
- ✓Diners Club — 14 digits, prefix 300-305, 36, or 38
- ✓JCB — 16 digits, prefix 35
- ✓UnionPay — 16-19 digits, prefix 62
- ✓Maestro — 12-19 digits, prefix 5018/5020/5038/5893/6304/6759/676x
- ✓Mir — 16-19 digits, prefix 2200-2204
- ✓RuPay — 16 digits, prefix 508x, 6069, 607x, 6521-6522
- ✓Luhn (mod-10) checksum per ISO/IEC 7812
- ✓Brand-aware visual formatting (4-4-4-4, 4-6-5, 4-6-4)
Limits & Performance
- •File Size: Validate one card at a time; generate up to 25 per request
- •Validations: Synchronous, in-browser — typically < 1 ms per card
- •Response Time: Instant — no network round-trip, for either validation or generation
- •Browsers: All modern browsers; works offline once the page is loaded
Pro Tips
- Strip non-digit characters before validating — the tool does this automatically, but if you're embedding the same logic, remember spaces and dashes are common in pasted card numbers.
- For brand detection, prefix-matching alone isn't enough at scale — always combine with length and Luhn checks before treating a brand as 'confirmed'.
- Mir, RuPay, and UnionPay are commonly missed by Western validators — if you sell internationally, make sure your form recognises them or you'll silently reject valid cards.
- For Cypress/Playwright tests, use the test PANs from this tool rather than randomly-generated numbers — you'll get consistent brand detection across runs.
- Treat the region badge as a sanity-check signal, not an authoritative issuer lookup. A Visa card can be issued anywhere in the world; only the brand-specific networks (UnionPay, RuPay, Mir, JCB) imply a strong region.
- Never log full PANs in your application or analytics — even validation failures should be redacted (typically `****-****-****-1234`).
- If you need true BIN-to-bank-and-country lookup for fraud screening, use a paid commercial BIN API (BinList Pro, BinTable, IINAPI) — but ship that as a separate service so your validation tool stays client-side.
- Generated PANs are random within their brand's prefix range — re-clicking Generate gives you a fresh batch every time, so you can produce non-overlapping fixtures across multiple test runs.
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