Free Image to Base64 Converter Online
Convert any image to a Base64 string instantly — or decode Base64 back to an image. Get ready-to-use HTML, CSS, and JavaScript code snippets. Supports batch processing, data URI format, line wrap control, and full privacy with zero server uploads.
The only free tool that combines encode, decode, batch conversion, and professional code snippets all in one place.
Unlimited Use
100% Private
No Upload
Forever Free
Everything Developers Need in One Tool
Built for real workflows — from embedding images in HTML emails to decoding unknown Base64 strings.
Two-Way Conversion
Encode images to Base64 and decode Base64 strings back to images — all in one interface. Switch between tabs instantly. No other free tool combines both directions this cleanly.
Batch Processing
Upload multiple images at once and convert them all simultaneously. Each image gets its own output panel with individual copy and download controls — a massive time saver.
Ready-to-Use Code Snippets
One-click copy of a complete HTML img tag, a JavaScript variable assignment, and a CSS background-image rule — paste directly into your project with zero extra work.
3 Output Formats
Toggle between Raw Base64 (string only), Data URI (data:image/png;base64,...), and CSS format. Every use case covered with one click.
Line Wrap Control
Toggle 76-character line breaks for MIME and email client compatibility. Essential for developers embedding images in HTML emails where strict line length is required.
File Size & Overhead Stats
See original file size, Base64 string length, and the exact overhead percentage. Base64 always adds ~33% — understand what embedding that image will cost your page weight.
Complete Privacy
All encoding and decoding happens entirely in your browser. No images, strings, or metadata are ever sent to a server. Your logos, screenshots, and assets stay on your device.
Download as .txt
Download any Base64 output as a plain .txt file for long-term storage, version control, or sharing with teammates — useful for large strings impractical to keep in clipboard.
Instant & Offline Ready
Conversion is instant with no server round-trip. Once loaded, the tool works completely offline. Ideal for restricted environments or working on the go.
Who Uses This Tool?
From front-end developers to email engineers — Base64 conversion is a universal need.
Web Developers
Embed images directly in CSS or HTML to eliminate extra HTTP requests and speed up page load for small icons and logos.
Email Engineers
Inline images in HTML emails to prevent broken image links, with proper 76-char MIME-compliant line wrapping for all email clients.
App Developers
Store small UI assets as Base64 strings in config files or JSON payloads, avoiding extra asset management complexity.
QA & Debuggers
Decode unknown Base64 strings from API responses, logs, or data dumps to instantly visualise what image is being transmitted.
Frequently Asked Questions
What image formats are supported?
The tool supports all common image formats: PNG, JPEG/JPG, GIF, WebP, SVG, BMP, and ICO. For the decode tab, any valid Base64 string with a supported MIME type will be accepted and previewed instantly.
Why does Base64 make the file larger?
Base64 encoding represents binary data using only 64 printable ASCII characters. Every 3 bytes of binary become 4 characters of Base64 — a fixed 33% size overhead. Our tool displays this so you can make an informed decision.
Is my image data sent to any server?
No. Every byte of processing happens inside your browser using the FileReader API and native JavaScript. Nothing is uploaded, transmitted, or stored externally. You can disconnect from the internet after loading and the tool works perfectly.
What is the difference between the three output formats?
Raw Base64 gives you the encoded string with no prefix. Data URI includes the full data:image/png;base64, prefix ready to paste into a src attribute. CSS Format wraps the Data URI in url("...") so you can paste it directly into a background-image property.
What is 76-character line wrap and when do I need it?
The MIME specification (RFC 2045) requires Base64-encoded data be split into lines no more than 76 characters. Most browsers handle long strings fine but some legacy email clients reject them. Enable this when embedding images in HTML emails.
How many images can I convert at once with batch mode?
You can drop or select as many images as you like. Since all processing is local, the only practical limit is your browser's available memory. For most use cases, batches of up to 50 images work smoothly.
Can I decode a Base64 string if I don't know the image type?
Yes. The tool attempts to auto-detect the image type from the Base64 header bytes. If detection fails, it falls back to PNG. You can also manually override the MIME type from the dropdown.
Should I always embed images as Base64 in my website?
Not always. Base64 is best for small images (under 5KB) like icons where eliminating an HTTP request outweighs the 33% overhead. For large images or anything that changes frequently, standard external file references are more efficient.
Understanding Base64 Image Encoding
Base64 is a binary-to-text encoding scheme that represents binary data — such as images — as a sequence of printable ASCII characters. Originally designed for email transmission, it now serves a much wider purpose in web development, APIs, data storage, and configuration files.
Why Developers Embed Images as Base64
Every external image on a web page requires its own HTTP request. For pages with many small icons or decorative elements, these requests add latency and slow down page load. By encoding small images as Base64 and embedding them directly into HTML or CSS, developers eliminate those requests entirely. Data URIs are accepted by all major browsers in src attributes, CSS background-image properties, and JavaScript image objects.
The 33% Overhead Trade-Off
Base64 encoding is not free. Because it converts every 3 bytes of binary data into 4 characters, the resulting string is always approximately 33% larger than the original file. For a 10KB PNG, the Base64 string will be around 13.3KB. Our tool shows you the original size, the Base64 size, and the overhead percentage for every conversion so you can make an informed engineering decision rather than blindly embedding everything.
Base64 in HTML Emails
Many email clients block external images by default, requiring users to click "Load Images" before they display. Embedding images as Base64 inline solves this — the image is part of the email itself and displays immediately. The MIME specification (RFC 2045) mandates that Base64 data must be split into lines no longer than 76 characters. Our line wrap toggle generates MIME-compliant output that works correctly with all major email clients including Outlook, Gmail, and Apple Mail.
Decoding Base64: The Reverse Problem
When you encounter a Base64 string in an API response, log file, database dump, or configuration file, you often need to see what image it represents. Our decode tab accepts any Base64 string — with or without the data URI prefix — and renders the image immediately. Auto-detection handles the MIME type in most cases, with a manual override available when needed.
Privacy and Security in Image Conversion
Many online Base64 tools upload your images to a server for processing — a significant privacy risk. Our tool performs every operation locally in your browser using the FileReader API and native JavaScript atob/btoa functions. Nothing leaves your device. The tool works offline, there are no accounts, and there is no logging of any kind. Your logos, screenshots, wireframes, and personal photos stay completely private.