Base64 Encoder & Decoder

Encode text and files to Base64 or decode back — entirely in your browser

100% local
Plain Text / File
Base64 Output

Output will appear here

Secure Client-Side Base64 Encoder & Decoder

Encode text and files to Base64, or decode back to plain text — entirely in your browser using browser-native APIs. Supports URL-safe Base64, file encoding, and UTF-8 handling. No uploads, no server, no tracking.

How It Works: Browser-Native Encoding

Text encoding uses the TextEncoder and btoa() APIs built into every modern browser. File encoding uses the FileReader API — no third-party library, no upload, no latency.

  • Instant encoding — result appears as you type.
  • Handles UTF-8, emojis, and multi-byte characters correctly.
  • Encode files (images, PDFs, binaries) to Base64 strings.

Why It's Safe: No Transmission

Many Base64 tools send your input to a backend for processing. This puts API keys, authentication headers, and sensitive file contents at risk. noserver uses only browser-native APIs — your data stays in local memory and is never transmitted.

  • Safe for encoding API keys and auth tokens.
  • File contents never leave your device.
  • Fully functional offline after first page load.

Frequently Asked Questions

Does NoServer upload my data when encoding Base64?
No. Encoding and decoding uses browser-native btoa() and atob() APIs. No network requests are made and no data is ever transmitted to any server.
Is it safe to encode credentials or tokens here?
Yes. Processing happens entirely in your browser's local memory. API keys, passwords, and secrets are never sent over the network or stored anywhere outside your browser tab.
Can I encode files to Base64?
Yes. Drop any file — images, PDFs, binaries — and get the Base64-encoded string instantly. The FileReader API handles this locally without any upload.
What is URL-safe Base64?
Standard Base64 uses + and / that must be percent-encoded in URLs. URL-safe Base64 replaces them with - and _ so the output works directly in URLs and HTTP headers without escaping.
Can I decode Base64 back to the original text?
Yes. Paste any Base64 string and click Decode. The tool handles standard and URL-safe variants and automatically repairs missing padding characters.
What character encoding does it use?
The encoder uses UTF-8 by default, which handles international characters, emojis, and multi-byte sequences correctly — unlike the raw btoa() which only supports Latin-1 characters.
Can I use this offline?
Yes. Once the NoServer application loads in your browser, all Base64 operations run entirely offline. The encoding engine requires no network access.
How does noserver compare to base64encode.org?
base64encode.org and similar tools send your text or file data to their servers. noserver uses browser-native APIs — your data never leaves your device, making it safe for secrets, credentials, and sensitive file contents.

Common Use Cases

HTTP Basic Auth Headers

Encode username:password for the Authorization: Basic header safely without pasting credentials into a server-side tool.

Embed Images in HTML/CSS

Convert images to Base64 data URIs for inline embedding in HTML email templates or CSS backgrounds without an external CDN request.

Decode JWT Payloads

Manually decode the Base64url-encoded header and payload segments of a JWT token to inspect claims without a dedicated JWT tool.

noserver vs base64encode.org vs base64.guru

Tools like base64encode.org and base64.guru transmit your input to their backend servers for encoding. For plain text this may seem harmless, but when encoding API keys, authorization headers, or sensitive file contents, that transmission is a real security risk. noserver runs the entire encode/decode pipeline using browser-native TextEncoder, btoa(), and FileReader APIs. Zero network requests, zero server logs, works offline.

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