How does the tool know which card network a number belongs to?

It reads the first few digits, the Issuer Identification Number (IIN, also called the BIN), and matches them to published ranges each network owns. For example 4 is always Visa, 51 through 55 and 2221 through 2720 are Mastercard, 34 and 37 are American Express. Type 4111 1111 1111 1111 and it reports Visa straight away; type 5500 0055 5555 5559 and it reports Mastercard.

Which networks can it recognise?

Visa (prefix 4), Mastercard (51-55 and 2221-2720), American Express (34 and 37, 15 digits), Discover (6011, 65, 644-649), JCB (3528-3589), Diners Club (36, 38, 300-305) and UnionPay (62). A number whose prefix falls outside every published range comes back as Unknown, which usually means a typo in the leading digits or a smaller regional scheme the tool does not list.

What does the Luhn check add?

Luhn is a mod 10 checksum that catches most single-digit typos and many swapped-digit mistakes. The tool runs it so you can see whether the digits form a structurally valid number. Note the limit: a random 16-digit string passes Luhn roughly one time in ten, so passing is not proof the card is real, issued, or funded. Brand detection answers who; Luhn answers only whether the math checks out.

Why does American Express look different from the others?

Amex cards are 15 digits and start with 34 or 37, while Visa and Mastercard are usually 16. The tool shows the expected length for the detected network next to the digit count, so if you paste a 16-digit number that starts with 34 it flags the length as unusual for Amex, a quick hint that something was mistyped.

Is this safe to use, and does my card number leave the page?

It is safe in the sense that detection runs entirely in your browser with plain JavaScript. No network request carries the number, nothing is logged or stored, and the number is deliberately kept out of the URL so a shared link can never leak it. Even so, treat any web form with caution and use a published test number such as 4111 1111 1111 1111 rather than a real card from your wallet.

Where do I get a test number to try this with?

Use the well-known network test PANs, for example 4111 1111 1111 1111 (Visa), 5500 0055 5555 5559 (Mastercard), 3400 0000 0000 009 (Amex) or 6011 0000 0000 0004 (Discover). If you need a batch of fresh, Luhn-valid samples, the linked credit card test number generator produces them, and the Luhn validator explains the checksum digit by digit.

Label a card field in a checkout UI as the user types

You are building a payment form and want the little brand badge to flip to Visa or Mastercard the moment enough digits arrive. Paste a few test PANs here to confirm where each brand becomes unambiguous — Amex resolves at two digits (34/37), Mastercard needs the 2-series range check — so you set the right trigger point in your own input handler instead of guessing the prefix rules.

Sanity-check a BIN range before wiring it into routing logic

Your gateway routes transactions by network, and a spec hands you a BIN like 622126. Drop a number with that prefix in and the tool confirms it reads as Discover, not UnionPay, before you hardcode the range. Catching an overlapping range on a test number is far cheaper than catching it on a live decline.

Triage a support ticket that says "my card was rejected"

A user pastes the card type they think they have. Run the leading digits (a published test number, never their real one) and you can tell whether the brand they expect matches the prefix, or whether they fat-fingered a digit and the length no longer fits the network. The Luhn flag separates a typo from a genuinely declined card.

Teach how BIN ranges and the Luhn checksum actually work

Walking a junior engineer or a class through card formats, you want live examples, not slides. Type 4111 1111 1111 1111 and watch it report Visa plus a passing Luhn; change one digit and watch Luhn fail while the brand stays Visa. The split between prefix detection and checksum becomes obvious in a few keystrokes.

Credit Card Type Detector — Brand From BIN Prefix

Read the card network from a number's BIN prefix — Visa, Mastercard, Amex, Discover, JCB, Diners, UnionPay — plus Luhn check, 100% in your browser

Runs locally
Category Developer & DevOps
Best for Formatting, validating, shrinking, or inspecting code-adjacent text.

Note: Do not paste a real card number. This runs entirely in your browser and nothing is sent or stored — but as a habit, use a published test number.

Card number to identify

Do not paste a real card number. This runs entirely in your browser and nothing is sent or stored — but as a habit, use a published test number.

Enter a number above to read its network.

What this tool does

Paste a card number and this detector tells you which network it belongs to by reading the BIN/IIN prefix — the leading digits that issuers map to a brand. Visa starts with 4, Mastercard sits in 51-55 plus the newer 2221-2720 range, American Express uses 34 or 37, Discover covers 6011, 65 and 644-649, JCB runs 3528-3589, Diners Club uses 36 and 38, and UnionPay begins with 62. Alongside the brand it runs the Luhn (mod 10) checksum so you can see whether the digits form a structurally valid number, and it tells you the length each network normally issues so a mistyped PAN stands out. This is identification by prefix, not a balance or fraud check: a number that matches Visa and passes Luhn is still not proof of a real, issued, funded card. Everything runs in the browser. Nothing is sent, logged, or stored, and the number is never written into the URL — use a published test number, never a real card.

Tool details

Input: Numbers; The page exposes text boxes, numeric controls, file pickers, or structured inputs depending on the tool.
Output: Live result + Copy; The result area focuses on usable output, with copy, download, or preview actions when supported.
Privacy: Browser-side processing; The main tool logic does not call an external API, so inputs normally stay in the current tab.
Save / share: Shareable URL state; Key settings are encoded in the URL so another person can reopen the same setup.
Performance budget: Initial JS <= 9 KB; No WASM budget is declared, keeping the tool quick to open on mobile.
Best fit: Developer & DevOps · Developer; Category and role tags drive related tools, internal links, and quick fit checks.

How to use

1. Input

Paste or drop your content into the tool panel.
2. Process

Click the button. All processing is local in your browser.
3. Copy / Download

Copy the result or download to disk in one click.

How Credit Card Type Detector fits into your work

Use it in the small gaps between coding, reviewing, debugging, and shipping.

Developer jobs

Formatting, validating, shrinking, or inspecting code-adjacent text.
Preparing snippets for documentation, tickets, commits, or handoff.
Checking a small payload quickly without switching tools.

Developer checks

Run irreversible transforms like minify or obfuscate on a copy.
Keep secrets out of pasted snippets unless the tool explicitly stays local.
Use your normal tests or linter before shipping transformed code.

Good next steps

These links move the current task into a more complete workflow.

Real-world use cases

Label a card field in a checkout UI as the user types
You are building a payment form and want the little brand badge to flip to Visa or Mastercard the moment enough digits arrive. Paste a few test PANs here to confirm where each brand becomes unambiguous — Amex resolves at two digits (34/37), Mastercard needs the 2-series range check — so you set the right trigger point in your own input handler instead of guessing the prefix rules.
Sanity-check a BIN range before wiring it into routing logic
Your gateway routes transactions by network, and a spec hands you a BIN like 622126. Drop a number with that prefix in and the tool confirms it reads as Discover, not UnionPay, before you hardcode the range. Catching an overlapping range on a test number is far cheaper than catching it on a live decline.
Triage a support ticket that says "my card was rejected"
A user pastes the card type they think they have. Run the leading digits (a published test number, never their real one) and you can tell whether the brand they expect matches the prefix, or whether they fat-fingered a digit and the length no longer fits the network. The Luhn flag separates a typo from a genuinely declined card.
Teach how BIN ranges and the Luhn checksum actually work
Walking a junior engineer or a class through card formats, you want live examples, not slides. Type 4111 1111 1111 1111 and watch it report Visa plus a passing Luhn; change one digit and watch Luhn fail while the brand stays Visa. The split between prefix detection and checksum becomes obvious in a few keystrokes.

Common pitfalls

Treating a brand match plus a passing Luhn as proof the card is real. Both only check format. A made-up number that starts with 4 and happens to pass the mod-10 checksum reads as a valid-looking Visa, yet no account exists behind it. Use this to identify and format-check, never to authorise.
Pasting a real card number into a web tool. Even though this one runs fully client-side and keeps the number out of the URL, the safe habit is to use a published test PAN like 4111 1111 1111 1111. Save the real card for the actual checkout, behind the merchant's PCI-compliant form.
Ignoring the expected-length hint. A number that starts with 34 but has 16 digits is not a normal Amex, which is 15. When the detected brand and the digit count disagree, a digit was probably added or dropped, so fix the input before trusting the result.

Privacy

Detection is plain JavaScript that runs inside your browser tab. The card number you type is held in component memory only: it is never sent over the network, never logged, never stored, and — unlike most tools here — it is deliberately kept out of the URL, so there is no shareable link that could carry it into someone's access log. The copy button copies the identification result (brand, Luhn, length), never the number itself. Still, the right habit on any web form is to use a published test number such as 4111 1111 1111 1111 rather than a card from your wallet.

FAQ

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Credit Card Type Detector — Brand From BIN Prefix

What this tool does

Tool details

How to use

1. Input

2. Process

3. Copy / Download

How Credit Card Type Detector fits into your work

Developer jobs

Developer checks

Good next steps

Real-world use cases

Label a card field in a checkout UI as the user types

Sanity-check a BIN range before wiring it into routing logic

Triage a support ticket that says "my card was rejected"

Teach how BIN ranges and the Luhn checksum actually work

Common pitfalls

Privacy

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