2026-10-03
Most online image to Base64 converters work the same way: you choose a file, the site sends it to a server, and a text string comes back. For a public logo that is harmless. For a screenshot of an internal dashboard, a scanned ID or an unreleased design it is an upload you did not need to make, because turning bytes into Base64 is something your browser can do on its own.
Image to Base64 has two modes in one page.
The file is read with the browser's own FileReader, so nothing leaves your device.
Base64 makes the data about a third larger, and an inlined image cannot be cached on its own the way a separate file can. That makes it a good fit for small things: a tiny icon in a CSS file, a placeholder, a single image in a self-contained HTML page or a JSON fixture, a logo in a README preview. It is a poor fit for photos and anything large, where a normal file with caching is better. Support for data URI images in email is inconsistent, so do not rely on it there.
Your build tool. If you are inlining assets for a web app, a bundler can do it for you. Vite, for example, inlines small assets as Base64 automatically below a size limit that you can configure. A converter page is for one-off cases, not for the build.
The command line. If you already work in a terminal, the base64 command on macOS and Linux does the same job for a file you have on disk, and it is easy to script.
Large images. For anything beyond a few kilobytes, shrink it first. Image Compressor and Image Resizer run in the browser too, and Image Converter can switch a PNG to a smaller WebP before you encode it.
For text rather than images use the Base64 Encoder. For documents there are PDF to Base64 and Base64 to PDF.
If you want a Base64 string or a data URI for an image you would rather not hand to a third-party server, try Image to Base64. If the image is large or the job is part of a build, use your bundler or the command line instead.