⌘ K
eui-48 · colon · hyphen · batch

Validate any MAC address with a regex

Check EUI-48 MACs with colon or hyphen separators, single or batch. Runs locally.

MAC Address Validator
Mode
single
one value
Valid
1
ok
Invalid
0
fail
Pattern
mac
EUI-48
Mode
input · single value
samples:
output · result
okValid
Pattern · EUI-48 /^(?:[0-9A-Fa-f]{2}[:-]){5}[0-9A-Fa-f]{2}$/
Quick Start

How to validate a MAC address

Type or paste one or many MACs. Both AA:BB and AA-BB separators are accepted.

  1. 01

    Pick mode

    Single for one MAC, batch for a list (one per line).

    Patterns compile through the JavaScript RegExp constructor, so syntax errors surface immediately and engine quirks like Unicode property escapes (\p{L}) work when the u flag is on.

    patternECMAScriptliterallive
    input · literalmode · regex
    Single | Batch
    loaded · ECMAScriptPCRE · ready
  2. 02

    Type or paste

    Mixed case is fine. Colons or hyphens both validate.

    Each flag character mirrors the ECMAScript literal: g enables iteration, i folds case, m anchors per line, s lets . match newlines, u unlocks proper Unicode, y is sticky, and d emits indices.

    flagsoptionsg · i · mlive
    config · optionsvalue · flags
    AA:BB:CC:DD:EE:FF
    flags applied · liveECMA · live
  3. 03

    Read the verdict

    Each line gets a pass/fail. The pattern is shown beside.

    Watch for catastrophic backtracking on nested quantifiers — a common ReDoS source. The tool caps match counts to keep the page responsive on pathological patterns.

    matchgroupshighlightReDoS-safe
    run · outputresult · matches
    ok AA:BB:CC:DD:EE:FF
    matches · livegroups · live
  4. 04

    Copy or export

    Grab the output as JSON, CSV, or plain text — ready for your editor or pipeline.

    Copy writes via navigator.clipboard.writeText; downloads use a Blob and object URL, so nothing transits the network and the output is byte-identical to what you see on screen.

    copyexportclipboardblob
    export · exportedready · saved
    Copied
    ready to shipsuccess
Pro tips

Regex patterns that don't melt down

Use named groups

(?<year>\d{4}) reads better than $1 and survives reordering. Supported in ECMAScript 2018+.

Anchor strictly

Use ^/$ with the m flag when matching whole lines. Without anchors, partial matches sneak through.

Avoid catastrophic backtracking

Nested quantifiers like (a+)+ can explode. Run patterns through ReDoS Detector first.

Escape every literal

Backslash any meta character you want literally: \.\$\^\*\+\?\(\)\[\]\{\}\|\\.

Test edge cases

Empty string, single character, unicode, the maximum length you expect — write fixtures for each.

Patterns aren&rsquo;t parsers

Don’t parse HTML, JSON, or balanced parens with regex. Use a proper parser when the grammar is recursive.

Related toolsUuid ValidatorIpv4 ValidatorIpv6 ValidatorRegex TesterRegex LibraryRegex Cheatsheet
Use Cases

When to validate MACs

Network audits, asset inventory, infra automation.

Inventory imports

Validate MACs before adding to CMDB. Compiles through the JavaScript RegExp constructor — engine quirks (Unicode property escapes, sticky matching, named groups) work when their flags are on. Error messages cite the exact position of any syntax issue.

ReDoS-safe

DHCP scopes

Confirm a reservation list parses. Pairs with the ReDoS detector to catch catastrophic backtracking before you deploy. A pattern that handles 1k-character input fine can become a denial-of-service vector on attacker-controlled 1M-character input.

ECMA-compliant

Firewall rules

Check MAC-based ACL inputs. Output exports as JavaScript, Python re, Java util.regex, .NET System.Text.RegularExpressions, PCRE, and POSIX — language quirks are highlighted on conversion so you don't ship a JS-only pattern to a Go service.

spec-grade

Audit asset reports

Find malformed MAC entries in CSV exports. Capture groups (named or numbered) round-trip cleanly into replacement strings, JSON output, or CSV extraction without re-typing. Backreferences ($1, ${name}) preserve semantics across languages.

cross-engine

Wi-Fi RADIUS

Validate MAC auth lists. Test against edge cases — empty input, single character, max length, multibyte boundaries — to catch off-by-one and zero-length match bugs before they reach production.

test-ready

Lab automation

Check provisioning inputs before applying. All matching runs client-side so secret patterns never leave the browser. Useful when the pattern itself is sensitive (PII regexes, internal data formats, security filters).

production-ready
FAQ

Frequently asked questions

This validator targets EUI-48 (the common 6-octet MAC). EUI-64 needs a separate regex.
No — A-F and a-f both validate. The pattern uses [0-9A-Fa-f].
Not currently — that's the dot-separated Cisco format. Add it via the Regex Builder if you need it.
Rejected — the regex requires consistent : or - throughout.
No. The tool runs entirely in your browser — your pattern and sample text never leave the page.
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