Base64 Decode & Encode — Free Online Decoder and Encoder

Base64 Decode & Encode — Free Online Decoder and Encoder. Free online Base64 decoder and encoder. Decode Base64 strings to plaintext or encode any text to Base64 instantly — 100% client-side, no data sent to servers.

Use our free online Base64 decoder and encoder to convert strings in seconds — no installation, no server uploads, 100% private. To decode Base64, paste your encoded string in the decoder panel and get the original plaintext instantly.

To encode to Base64, type or paste any text and copy the Base64 output. The tool also supports URL-safe Base64 (RFC 4648 §5), which replaces + with - and / with _ for use in URLs and filenames. Need to encode an entire file?

Use our companion Base64 File Converter. Every Base64 encode and Base64 decode operation runs entirely in your browser using the Web Crypto API — your strings, passwords, and API keys never leave your device.

Common uses include encoding credentials for HTTP Basic Authentication headers (Authorization: Basic dXNlcjpwYXNz), embedding small text payloads in data URIs, storing binary data in JSON or XML, and debugging JWT tokens whose payload is Base64url-encoded.

The auto-detect mode identifies whether your input looks like a Base64 string or plaintext and switches direction automatically — ideal when you are not sure which direction you need.

Frequently asked questions

How do I decode a Base64 string?

Paste the Base64 string into the Base64 to string panel. The decoded text appears immediately below it. If the string uses the URL-safe alphabet (with - and _ instead of + and /), switch on the URL-safe option first.

Is Base64 a form of encryption?

No. Base64 is an encoding, not encryption: anyone can decode it without a key. It is used to represent binary or special characters as plain ASCII text, for example in email attachments, data URIs, JSON payloads and HTTP Basic Authentication headers. Use real encryption for secrets.

What is URL-safe Base64?

URL-safe Base64 (RFC 4648 section 5) replaces the + and / characters with - and _ so the result can be used in URLs, file names and JWT tokens without extra escaping. Enable the URL-safe switch when encoding or decoding such strings.

Why does my Base64 string end with = or ==?

The = characters are padding. Base64 encodes every 3 bytes as 4 characters, so when the input length is not a multiple of 3 the output is padded with one or two = signs to keep the length a multiple of 4.

Is my data uploaded to a server?

No. Encoding and decoding run entirely in your browser, so the text you paste, including passwords or API keys, never leaves your device.

How to use this online tool

Base64 Decode & Encode — Free Online Decoder and Encoder is designed for fast browser workflows when you need to format, validate, convert, decode, encode, generate, or inspect data without opening a heavy desktop app. Start with the input field or visible options, review the result, then copy or download the output for the next step.

Private processing in your browser

Base64 Decode & Encode — Free Online Decoder and Encoder keeps the normal processing step local in your browser. That is useful for code snippets, tokens, documents, configuration values, text samples, and other material that should not be sent to a remote service unless you explicitly choose to share it.

When this tool is useful

Use Base64 Decode & Encode — Free Online Decoder and Encoder for repeatable developer tasks, technical documentation, QA checks, quick conversions, debugging, content cleanup, and internal team workflows. The page focuses on clear inputs, immediate feedback, and output that is easy to reuse in code, reports, tickets, emails, or notes.

Practical tips

Before copying the final result, check important details such as spacing, casing, filenames, encoding, token structure, line breaks, or output format. Small checks prevent mistakes when the result is reused in source code, API requests, documentation, spreadsheets, or shared files.