Pattern

Regex for Alphanumeric password

8+ alphanumeric characters only.

The Alphanumeric password regex is ^[A-Za-z0-9]{8,}$ — copy it below, or open it in the explainer for a token-by-token breakdown.

The pattern

^[A-Za-z0-9]{8,}$

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What it matches

Password1
abc12345
LongPassword

What it doesn't match

short
pass word
pa$$word

Notes & gotchas

No special characters at all. Often required by legacy systems that don't handle symbols correctly. Provides limited security.

Code in your language

Use the explainer's Code tab to generate ready-to-paste snippets in JavaScript, Python, Java, .NET, Go, Ruby, and PHP for this pattern.

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Token-by-token breakdown

Every part of the pattern, left to right:

Token	Meaning
`^`	start of string (or line in multiline mode)
`[A-Za-z0-9]{8,}`	8 or more times: any of: uppercase letters, lowercase letters, digits
`$`	end of string (or line in multiline mode)

About this pattern

Password and credential validation patterns enforce policy rules. Modern guidance (NIST 800-63B) favors length over complexity.

Quick usage in different languages

This exact pattern — with the correct escaping and idioms for each language:

JavaScript: /^[A-Za-z0-9]{8,}$/.test(value)
Python: re.match(r"^[A-Za-z0-9]{8,}$", value)
Java: Pattern.compile("^[A-Za-z0-9]{8,}$").matcher(value).matches()
C# / .NET: Regex.IsMatch(value, @"^[A-Za-z0-9]{8,}$")
Go: regexp.MustCompile(`^[A-Za-z0-9]{8,}$`).MatchString(value)
Ruby: /^[A-Za-z0-9]{8,}$/.match?(value)
PHP: preg_match('~^[A-Za-z0-9]{8,}$~', $value)

The explainer’s Code tab regenerates these for any pattern you paste, and the downloadable cheat sheet bundles the breakdown, all seven snippets, and the pitfalls below onto one printable page.

Common pitfalls

Anchored to the whole string. This pattern uses ^ and $, so it requires the entire input to match. To find it inside a longer text, drop the anchors and use the global (g) flag.
ASCII letters only. [a-zA-Z] excludes accented and non-Latin letters (é, ü, ß, ñ, and non-Latin scripts). For international input use Unicode properties like \p{L} with the u flag.
Validate beyond format. Matching the format doesn't guarantee the value is real. Confirm the alphanumeric password against a source of truth (database, API, or checksum) where it matters.

Related patterns

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