Base64 Encoder / Decoder
Encode text to Base64, or decode back — free, instant, private.
How to Use the Universal Encoder / Decoder
- Pick a Tab: Choose Base64 Text, Image to Base64, URL, or HTML Entity depending on what you need to convert.
- Paste or Upload: Type your text, paste a string, or drag in an image file.
- Encode or Decode: Click the matching button — your result appears instantly in the output box.
- Copy or Download: Copy the result to your clipboard or download it as a file, ready to use.
Why Use This Tool
Developers run into the same handful of encoding problems constantly: a Base64 string needs decoding to check an API token or JWT payload, an image needs converting to a Base64 data URI for inline CSS or HTML, a URL breaks because of an unencoded space or special character, or user-submitted text needs escaping to safe HTML entities before it's safe to display. Instead of bookmarking four separate single-purpose converters, this all-in-one encoder decoder tool covers Base64, URL percent-encoding, HTML entity escaping, and image-to-Base64 conversion in one place — free, instant, and 100% private in your browser.
How It Works
Each mode uses the browser's own native conversion functions — UTF-8 safe btoa/atob for Base64 text, the FileReader API for image-to-Base64 conversion, encodeURIComponent/decodeURIComponent for URL percent-encoding, and safe DOM-based escaping for HTML entities. Nothing is uploaded anywhere; every conversion, in every tab, runs entirely on your own device.
Key Features
The Base64 Text tab handles UTF-8 safe encode/decode with an optional URL-safe mode, an Auto-Detect button, and a one-click Swap. The Image to Base64 tab accepts PNG, JPG, WebP, or SVG files via drag-and-drop and instantly generates ready-to-use HTML, CSS, and Markdown snippets alongside the raw Base64 string. The URL tab supports both Component and Full URI encoding modes, with an option to use + for spaces. The HTML Entity tab converts live as you type, with a running character and entity count, and preserves line breaks correctly. Switch between any of the four modes anytime without losing your work in the others.
Common Use Cases
Developers decode a Base64-encoded JWT payload segment to inspect its claims during debugging, or encode API credentials into a Basic Authentication header. Frontend developers embed small icons and logos directly into CSS using Base64 to cut down on extra HTTP requests. Marketers and API integrators encode UTM parameters or query values containing spaces and special characters before adding them to a link. Security-conscious developers encode user-submitted text into HTML entities before displaying it on a page, preventing HTML injection and XSS vulnerabilities. Technical writers escape angle brackets and ampersands when preparing HTML code examples for documentation.
Tips for Best Results
Remember that Base64 encoding is not encryption — it's a reversible text encoding, so never rely on it to protect sensitive data like passwords. Base64 increases file size by roughly 33%, so image-to-Base64 works best for small icons and logos rather than large photographs. Always test a percent-encoded URL in an actual browser address bar to confirm it resolves as expected. Always encode any user-generated content before inserting it directly into HTML to prevent cross-site scripting — this is a fundamental web security habit, not just a formatting nicety.
Privacy & Security
Because ToolNest processes everything entirely within your browser using client-side JavaScript, your files and text never leave your device — in any of the four modes. There is no server-side storage, no third-party analytics attached to your data, and no risk of a breach exposing something you converted months ago.
What's the difference between Base64, URL encoding, and HTML entity encoding?
Base64 turns any data (including binary like images) into safe text for things like API tokens; URL percent-encoding makes special characters safe inside a web address; HTML entity encoding makes characters like < and > safe to display inside a web page without being interpreted as code.
Is this the best free all-in-one encoder decoder tool available online?
It combines four commonly needed conversions — Base64 text, image-to-Base64, URL, and HTML entities — in a single free, instant, private tool, so you don't need to bookmark four separate converters.
Is Base64 the same as encryption?
No. Base64 is a reversible encoding format, not encryption — anyone can decode it without a key, so it should never be used to protect sensitive data.
How do I convert an image to Base64 for use in CSS or HTML?
Switch to the Image to Base64 tab, drag in your PNG, JPG, WebP, or SVG file, and copy the ready-made HTML <img> or CSS background-image snippet generated automatically.
Why does my URL break unless I encode it first?
Characters like spaces, ampersands, and question marks have special meaning in a URL; percent-encoding converts them into a safe %XX format so the link is transmitted and parsed correctly.
Why should I encode HTML entities before displaying user text on a page?
Encoding converts characters like < and > into safe entities, preventing malicious script tags from being interpreted as executable HTML — a basic defense against XSS attacks.
Does any of this run on a server, or is it fully offline-capable?
All four modes run entirely as JavaScript in your browser using native functions — nothing is uploaded, so the tool works even without a stable internet connection once the page has loaded.
Does the tool handle special characters and emoji correctly?
Yes — the Base64 mode uses UTF-8 safe handling and the HTML Entity mode preserves line breaks, so international characters and emoji convert correctly in both directions.