All The Validators logoAll The Validators

developer validator

Base64 Validator

Validate and decode standard or URL-safe Base64 entirely in your browser—no uploads or storage.

Results

Processing…
Status
Processing...
Details
Processing...
Decoded text
Processing...

How to use this validator

  1. Paste your Base64 or Base64URL text.
  2. Click validate to check the alphabet/padding and decode the content locally.
  3. If invalid, adjust padding or remove non-Base64 characters and retry.

Rules & checks

Accepts both standard Base64 and URL-safe Base64 (using - and _).

Accepts padded (=) and unpadded variants; decoding uses UTF-8 output.

Rejects malformed alphabets, bad padding, or non-Base64 characters.

Runs entirely in-browser; nothing is uploaded or stored.

Inputs explained

  • Base64 string

    Paste the encoded text. Standard or URL-safe forms are fine, with or without = padding. Keep under ~500 KB for best in-browser performance.

When to use it

  • Decode Base64 payloads from webhooks, cookies, or query parameters
  • Validate URL-safe Base64 segments before persisting or parsing
  • Spot padding/alphabet issues when exchanging tokens between systems
  • Check encoded environment variables or config blocks locally

Common errors

  • Non-Base64 characters (anything outside A–Z, a–z, 0–9, +, /, -, _ and = for padding)
  • Missing or extra padding when using standard Base64
  • Mixing URL-safe alphabet (-, _) with + or / in the same string
  • Hidden whitespace/newlines inside the encoded text

Limitations

  • Decodes to UTF-8 text; binary payloads may show garbled characters.
  • Does not fetch remote files—paste the Base64 string directly.
  • Very large blobs can be slow in the browser; keep to a few hundred KB.
  • Validation is alphabet/padding only; content semantics are not checked.

Tips

  • If a JWT or URL uses Base64URL, expect - and _ and often no = padding.
  • Strip whitespace/newlines before validating if content was wrapped.
  • Do not paste secrets you should not handle in-browser; treat tokens carefully.
  • If you expect binary output, use hex display downstream instead of UTF-8 text.

Examples

Valid: standard Base64

  • SGVsbG8= -> Valid (decodes to "Hello")

Valid: URL-safe, unpadded

  • U29tZS11cmxfaWQ -> Valid URL-safe (decodes to "Some-url_id")

Invalid: bad characters

  • SGVsbG8$ -> Invalid (non-Base64 character $)

Invalid: broken padding

  • SGVsbG8== = -> Invalid (extra padding)

Deep dive

This Base64 validator supports both standard and URL-safe alphabets, with or without padding, and decodes locally for quick debugging of tokens, headers, and encoded payloads.

Use it to catch malformed Base64 before handing data to APIs or storage. Everything runs in your browser, so secrets are not uploaded or logged.

FAQs

Do you support Base64URL without padding?
Yes. URL-safe strings using - and _ work with or without = padding.
Is any data uploaded or stored?
No. Validation and decoding run fully in your browser and clear on refresh.
Why do I see strange characters after decoding?
The decoder outputs UTF-8 text. If your data is binary, view it as hex or keep it encoded.
Can I decode huge Base64 files?
Keep inputs to a few hundred KB for responsiveness. Use streaming/server tools for larger blobs.
Does this verify the content meaning?
No. It checks Base64 structure and decodes the bytes; it doesn’t validate the semantics of the payload.

Related validators

developer

JWT Decoder

Decode JWT headers and payloads client-side—no uploads, no signature verification, and no storage.

security

JWT Signature Validator (HS256)

Validate HS256 JWT signatures with a shared secret, fully client-side—no tokens or secrets ever leave your browser.

developer

Regex Tester

Test regex patterns against sample text with live matches and errors.

developer

UUID Validator

Check UUIDs (v1–v5) for proper formatting before using them in requests or logs.

security

Password Strength Checker

Score password strength with clear, local checks—length, variety, and guidance without sending data anywhere.

security

Password Entropy Calculator

Estimate password entropy (bits) in-browser to see how length and character sets impact strength.

format

JSON Validator

Check JSON syntax instantly, see exact parse errors, and keep everything local to your browser.

web

URL Validator

Validate HTTP/HTTPS URLs locally—parse host/path and catch malformed links before publishing or sending to APIs.

web

HTTP Security Headers Validator

Validate core security headers (HSTS, nosniff, frame options, referrer policy, permissions policy) entirely client-side.

All Base64 validation and decoding happen in your browser. Nothing is sent, logged, or stored.

Decoding only; do not paste secrets.