Base64 Encoder & Decoder — 100% Local, Instant

⚡ Quick answer: Base64 Encoder & Decoder: Encode and decode Base64 instantly — 100% in your browser. It runs 100% in your browser — nothing is uploaded, no account needed.

What Base64 actually does

Base64 takes any byte sequence — text, an image, a binary blob — and rewrites it using only 64 safe ASCII characters (A–Z, a–z, 0–9, plus, slash), padding the end with one or two equals signs. That makes it transit-safe: the payload survives form fields, URLs (with extra care), email bodies and JSON strings that would mangle raw bytes. It is encoding, not encryption — anyone can reverse it in one command, so never use it to hide a secret, and never put credentials in a Base64 string you think is "protected."

The two directions, when to use each

Encode when you are embedding a small file (a favicon, a generated thumbnail) into HTML or CSS as a data URI, or when an API expects a Base64 field. Decode when you receive such a payload — an error log containing a Base64 stack, a config value you suspect is just text — and want to read it back. Both directions are computed in your browser with the built-in btoa/atob primitives; the text you paste is processed locally and is never transmitted, which is the point of a privacy-first tool.

Watch-outs

Non-ASCII text must be UTF-8 encoded before Base64 — the tool handles that for you, but a naive btoa() call on Unicode throws. And if the output looks like it has line breaks or whitespace, strip them first: Base64 is one continuous alphabet, and stray characters break decoding.

How to encode or decode Base64 (3 steps)

1. Paste your text or Base64 string into the box.
2. Click Encode or Decode — the result appears instantly below. If decoding fails, the input likely isn't valid Base64 (wrong characters or missing padding).
3. Copy the result — or clear and go again. Everything stays on your device.

FAQ

• Why encode sensitive strings at all? Base64 makes binary-safe text (data URIs, headers, tokens in config) — but it is encoding, not encryption. Anyone can decode it, so never treat it as secret protection.
• Is Base64 safer than pasting a raw key into a converter site? Yes — a random converter logs whatever you paste. Here the key never leaves the browser, which is the whole point.
• Why do I get a decode error? Base64 uses A–Z, a–z, 0–9, plus +// (or URL-safe -/_) with = padding. Stray spaces, newlines mid-line, or a truncated string will fail.