Base64 Decoder Online — Uttir
Uttir

Base64 Decoder

Decode Base64 back into readable text, with clear errors for malformed input.

X LinkedIn Reddit Email

Base64 Decoder — Paste any standard Base64 string and get the original text back, including Unicode content encoded as UTF-8. Invalid characters or broken padding are reported with a clear explanation instead of a silent failure.

Decoding happens locally in your browser. Your data is never uploaded.

Was Base64 Decoder useful?

What is base64 decoder?

Paste any standard Base64 string and get the original text back, including Unicode content encoded as UTF-8. Invalid characters or broken padding are reported with a clear explanation instead of a silent failure.

Like the rest of Uttir, decoding runs entirely in your browser — handy for inspecting tokens, data URLs, and encoded payloads that you would rather not paste into a random website.

How to use it

  1. Paste Base64

    Whitespace-free standard Base64 with optional = padding.

  2. Read or copy the result

    The decoded text appears live on the right.

Examples

Round trip

Decoding the encoder’s example returns the original text.

aGVsbG8gd29ybGQ=

Result: hello world

Frequently asked questions

Related guides

The Anatomy of a Perfect Stack Trace

A stack trace is a map of where your code was when it crashed. Most people read it backwards. The actual bug is almost never where you think it is. Here is how to read a stack trace top-to-bottom, the four lines that matter, the seven lines that lie, and how to find the real bug in 30 seconds.

How to Read a JWT Token (Without Trusting the Sender)

A JWT is three base64 strings joined by dots. The middle one is the payload, and it is usually readable without any verification. The header tells you the algorithm. The signature is what you would verify to trust the contents. Here is how to read each part, with worked examples.

How to Convert an Image to Base64 (and When You Actually Should)

Base64-encoded images travel as text — useful in CSS, HTML emails, JSON APIs, and anywhere you cannot ship a real image file. The trade-offs, the practical limits, and a free browser tool that does the conversion without uploading anything.

Related tools

Base64 Encoder

Encode any text — including emoji and non-Latin scripts — into standard Base64.

JWT Decoder

Decode a JWT’s header and payload and check its expiration — without sending it anywhere.

Last reviewed: 2026-09-18