Is Base64 encryption?

No, and treating it like one is how secrets leak. Base64 is just an alphabet swap — anyone who sees the string can decode it in a single function call, no key required. If your goal is to hide an API key, a password, or anything sensitive, reach for real crypto (AES, libsodium, your platform's KMS). Base64 is for transport, not secrecy.

Why does the encoded output sometimes end with = signs?

Those are padding, not corruption. Base64 outputs in groups of 4 characters, so if your input isn't a multiple of 3 bytes, the encoder pads the last group with one or two = to fill it out. URL-safe Base64 typically strips the padding (decoders re-add it on the other side) — both forms are valid.

Why does my Urdu/emoji text get encoded weirdly?

It shouldn't, with this tool. The converter uses TextEncoder to produce UTF-8 bytes first, so Urdu, Arabic, Chinese, and emoji round-trip cleanly. If a server-side decoder is mangling them into question marks, the bug is on that end — it's almost certainly assuming Latin-1 instead of UTF-8. Fix the decoder, not your input.

What's the size overhead?

Roughly 33% bigger. Every 3 bytes of input become 4 Base64 characters, so a 1 MB file lands around 1.37 MB encoded. That's fine for tokens, signatures, and tiny inline assets. Painful if you're tempted to inline a 5 MB hero image as a data URL — for anything beyond a few KB, ship the binary separately and link it.

What's the difference between Base64 and Base64URL?

Base64URL is the URL-safe variant: it swaps + for - and / for _, then typically drops the = padding. That matters because + and / are reserved in URLs and inside JWT segments, where they'd silently break things. JWT, OAuth, and most modern web APIs use Base64URL — using standard Base64 there is one of the most common reasons a token "looks right" but never validates.

Base64 Encode / Decode (2026) | Premium Converters

Base64 is encoding, not encryption. Anyone who sees the string can decode it instantly. If your instinct is to base64-encode an API key before storing it in localStorage to "hide" it, stop — use real crypto or don't store it client-side at all.

URL-safe variant matters more than you think. Standard Base64 uses + and / which break inside URLs and JWTs. URL-safe swaps them for - and _ and drops the = padding. JWT segments will never validate if you use the wrong variant — check before you debug deeper.

Output is ~33% larger than input. A 1MB file becomes ~1.37MB encoded. Fine for tokens and tiny inline assets; painful if you're tempted to embed a 5MB hero image as a data URL. For anything bigger than a few KB, ship the binary separately and reference it.

UTF-8 trips legacy decoders. This tool encodes Urdu, Arabic, Chinese, and emoji as UTF-8 bytes first, so they round-trip cleanly. If a server-side decoder mangles them into question marks, it's assuming Latin-1 — fix the decoder, not your input.

The trailing = signs are padding, not corruption. Base64 outputs in groups of 4 characters; if your input length isn't a multiple of 3 bytes, the encoder pads with one or two = to fill out the last group. URL-safe encoders usually strip them and decoders re-add them. Both are valid.

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Base64 Encode / Decode