BYTETOOLS

License Key Generator

Generate software licence keys from a mask like XXXXX-XXXXX-XXXXX-XXXXX, with a Luhn mod N or MOD 97-10 check character so your app can reject typos offline.

20
Random characters
32
Alphabet size
100.0 bits
Entropy
10^30.1
Possible keys

License keys

Press “Generate keys” to create a batch from the mask above.

Check a key

Paste one of the keys above, or one a customer has given you, to see whether its check character adds up.

Every random character comes from crypto.getRandomValues with rejection sampling, so no character is even slightly more likely than another. The check character is not security — it is a courtesy: it lets your installer reject a mistyped key instantly and offline, before it ever contacts your licence server. Luhn mod N catches every single-character slip and nearly every swapped pair; MOD 97-10 adds two decimal digits and catches the same class of mistake.

Keys are generated in your browser and never uploaded or stored anywhere, so copy or download the batch before you close the tab. A checksum alone does not stop key sharing — pair these with server-side activation if that matters to your product.

What is the License Key Generator?

This tool builds product keys from a mask you control. Every X in the mask becomes a random character; dashes, letters and anything else are copied through untouched.

  • Mask-driven layout with any grouping and separator you like
  • Five alphabets including Crockford base32 and an unambiguous 30-character set
  • Luhn mod N or ISO 7064 MOD 97-10 check characters
  • Built-in verifier so you can test a key against the scheme
  • Entropy in bits and total keyspace shown for the mask you chose
  • Up to 5000 keys per batch with CSV and TXT download

How to use the License Key Generator

  1. 1

    Edit the mask so its Xs match the key shape you want, for example XXXXX-XXXXX-XXXXX-XXXXX.

  2. 2

    Choose an alphabet — Crockford base32 drops the easily confused I, L, O and U.

  3. 3

    Pick a check character scheme, or turn it off, and set how many keys you need.

  4. 4

    Press Generate keys, then copy the list or download it as CSV or TXT.

  5. 5

    Paste a key into the Check a key box to confirm your validation logic agrees.

About the License Key Generator

This tool builds product keys from a mask you control. Every X in the mask becomes a random character; dashes, letters and anything else are copied through untouched. Characters are drawn from your chosen alphabet using your browser's cryptographic random source with rejection sampling, so no character is even slightly more likely than another.

The optional check character is what makes a key useful offline. Luhn mod N appends one extra character from the same alphabet and catches every single-character typo along with almost every swapped pair. ISO 7064 MOD 97-10 appends two decimal digits and catches the same class of mistake. Paste any key into the verifier below to see it work.

Keys are generated in your browser and never uploaded, logged or stored, so copy or download the batch before you close the tab or it is gone for good. A checksum is a courtesy to your customers, not a security control — pair these keys with server-side activation if licence sharing actually matters to your product.

Frequently asked questions

What is a Luhn mod N check character?

It is the generalisation of the credit-card check digit to any alphabet size. Code points are doubled every second position from the right, the overflow is folded back in, and a final character forces the total to a multiple of the alphabet size. Any single wrong character breaks the sum.

Why does the default alphabet leave out I, L, O and U?

That is Crockford base32. I and L look like the digit 1, O looks like zero, and U is dropped so the encoding cannot accidentally spell certain words. Removing them means a customer reading a key over the phone makes far fewer mistakes.

Are these licence keys secure?

The randomness is, since it comes from crypto.getRandomValues. But a key that only has to match a checksum can be forged by anyone who works out the scheme. Use these as product keys checked against a server, not as the sole proof of a purchase.

How long should a licence key be?

Twenty characters of Crockford base32 gives about 100 bits of entropy, which is far beyond guessable. The four-group XXXXX-XXXXX-XXXXX-XXXXX shape is popular because it is long enough to be unguessable and still readable aloud.

Can I check a key without contacting a server?

Yes, that is exactly what the check character is for. Your installer recomputes it from the rest of the key and rejects a mismatch instantly, so an obvious typo never reaches your licence server or your support queue.

Will the same key ever be generated twice?

With a realistic mask the odds are astronomically small, and the tool also re-rolls within a batch if a duplicate appears. Across separate batches it cannot know what it produced before, so keep your issued keys in a database and check on insert.

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