About Base64 Tool
A fast, private utility for encoding and decoding Base64 — built for developers who care about their data.
What is this tool?
Base64 Tool is a free, open-source utility for encoding and decoding Base64 data. It supports plain text with full UTF-8 Unicode, images (PNG, JPG, GIF, WebP, SVG), and arbitrary files up to any size — though we recommend keeping files under 10 MB for smooth browser performance.
100% Client-Side
Every encoding and decoding operation happens entirely in your browser using built-in Web APIs (TextEncoder, FileReader, atob/btoa). No data is ever sent to a server. Your files, images, and text never leave your device — making this tool safe for sensitive content like API keys, tokens, and private documents.
How Base64 Works
Base64 encoding converts binary data into a set of 64 printable ASCII characters (A–Z, a–z, 0–9, +, and /). Every three bytes of input produce four characters of output. Padding with = characters ensures the output length is always a multiple of four.
URL-safe Base64 replaces + with - and / with _, and omits padding. This variant is safe for use directly in URLs, filenames, and other contexts where the standard characters would need escaping.
How to Use This Tool
Text mode
Type or paste any text into the left panel. The Base64-encoded result appears instantly on the right. Flip the direction toggle to decode — paste a Base64 string and get the original text back. Works with any Unicode content, including emoji and non-Latin scripts.
Image mode
Drag an image (PNG, JPG, GIF, WebP, or SVG) onto the drop zone or click to browse. The tool generates a data: URI you can paste directly into HTML or CSS. To reverse the process, paste any Base64 data URI and preview the decoded image — then download it.
File mode
Upload any file type to encode it as a Base64 string. To decode, paste the Base64 string, enter a filename with the correct extension, and download the reconstructed binary file. Best suited for files under 10 MB — larger files may slow down your browser tab.
URL-safe mode
Toggle the URL-Safe switch to switch between standard Base64 (+/=) and URL-safe Base64 (-_, no padding). Use URL-safe output in JWTs, query parameters, filenames, or anywhere + and / would need percent-encoding.
Why use this tool?
Most Base64 tools online handle text only, or scatter text, image, and file encoding across separate pages. This tool does all three in one place with a clean, distraction-free interface.
The bigger difference is privacy. Many online converters send your input to a server to process it — which means your API keys, private images, and sensitive files pass through infrastructure you don't control. Everything here runs locally in your browser using native Web APIs. No upload, no log, no trace.
It also handles UTF-8 correctly. The native browser btoa() function breaks on characters outside the Latin-1 range. This tool uses TextEncoder to handle the full Unicode range, so emoji, Arabic, Chinese, and other non-ASCII text encode and decode correctly.
Common Use Cases
- Embedding images as data URIs in HTML and CSS
- Encoding binary attachments for email (MIME)
- Storing binary data in JSON or XML payloads
- Encoding credentials for HTTP Basic Authentication
- Transferring binary data through text-only APIs
Ready to encode?
Jump into the tool — it's fast, free, and runs in your browser.