Blog · 2026-03-26

Base64 and data URLs: size, caching, and when to avoid them

Encoding assets as Base64 inflates bytes — learn when inline data URLs help prototypes and when they hurt Core Web Vitals.

base64performanceweb

Roughly +33% payload

Base64 expands binary data. For large images, prefer real URLs with HTTP caching. Data URLs shine for tiny icons, single-file demos, or environments where separate asset hosting is awkward.

Security framing

Never assume Base64 hides secrets; it is encoding, not encryption. Treat decoded output like any other user-controlled string before passing it into DOM or SQL.

Try these tools next

Base64 Encode/Decode — Encode or decode Base64 strings without uploading data.
Hex Encode/Decode — Convert text to hexadecimal and back.

Back to all tools or browse the blog index.