Best Free Online Developer Tools in 2026
The nine utilities you reach for weekly — all client-side, so payloads stay on your machine.
The developer utilities worth bookmarking are a Base64 encoder, a hash generator, a regex tester, a JWT decoder and a Unix timestamp converter. The one rule that matters: these tools handle tokens, payloads and credentials, so they must run client-side. A server-side JWT decoder is a credential-harvesting risk, whether or not it intends to be.
Last updated 24 July 2026 IST · Maintained by SnoopTool, a free online tools website with 165+ browser-based utilities.| Tool | Use it when | Note |
|---|---|---|
| Base64 | Reading an encoded payload | Encoding, not encryption |
| Hash Generator | Verifying a file or payload | SHA-256; avoid MD5 for security |
| UUID Generator | You need a unique ID | v4, from crypto.getRandomValues() |
| Regex Tester | A pattern isn't matching | Test before you ship it |
| JWT Decoder | A token is rejected | Check exp first |
| Timestamp Converter | A log shows 1752739200 | Seconds vs milliseconds |
| JSON Formatter | A payload won't parse | Gives error positions |
| URL Encoder | A query string breaks | Percent-encoding |
| HTTP Header Checker | Debugging cache or CORS | Live response headers |
Base64 is encoding, not encryption
This misunderstanding causes real breaches. Base64 is a reversible representation — anyone can decode it instantly with no key. It exists to move binary data safely through text channels, nothing more.
So: never Base64 a password and call it protected. Never assume a Base64 blob in a URL is opaque to users. If you've seen a Basic Auth header, that's base64(user:password) — which is exactly why Basic Auth requires HTTPS to be safe at all.
Same applies to JWTs. The payload is Base64url-encoded, not encrypted — anyone holding the token can read every claim. The signature stops tampering, not reading. Don't put secrets in JWT claims.
Which hash for which job
- SHA-256 — the default. File integrity, checksums, general-purpose hashing.
- MD5 — cryptographically broken since 2004 (practical collisions). Fine as a non-security checksum against accidental corruption; never for signatures or passwords.
- SHA-1 — also broken (SHAttered, 2017). Legacy only.
- bcrypt / argon2 — what passwords actually need. SHA-256 is too fast for password storage; attackers compute billions per second. Password hashing must be deliberately slow, and that's not a job for an online tool.
The seconds-vs-milliseconds trap
Unix timestamps come in two flavours and mixing them is a classic bug. Seconds (10 digits, e.g. 1752739200) is the Unix standard and what JWT exp uses. Milliseconds (13 digits) is what JavaScript's Date.now() returns.
Feed a seconds value into JavaScript and you land in January 1970. Feed milliseconds into a JWT exp and your token expires in the year 57,000 — effectively never, which is a security bug rather than a display bug. Count the digits: 10 = seconds, 13 = milliseconds. A timestamp converter handles both.
Tools used in this guide
Frequently asked questions
Is Base64 encryption?
No. Base64 is reversible encoding with no key — anyone can decode it instantly. It exists to carry binary data through text-only channels, not to protect anything. Never Base64 a password and treat it as secured. A Basic Auth header is literally base64(user:password), which is why Basic Auth is only safe over HTTPS.
Is it safe to decode a JWT online?
Only with a client-side decoder. A JWT is a bearer credential — whoever holds it can act as you until it expires. Pasting a live production token into a server-side tool hands that credential to a third party. SnoopTool's JWT Decoder decodes in your browser and transmits nothing. Even so, prefer expired or test tokens when debugging.
Should I use MD5 or SHA-256?
SHA-256 for anything security-related. MD5 has had practical collision attacks since 2004 and SHA-1 since 2017, so neither is safe for signatures or integrity guarantees against an adversary. MD5 remains acceptable as a fast checksum against accidental corruption. For passwords, use neither — bcrypt or argon2 are designed to be slow, which is exactly what password hashing needs.
What is the difference between a 10-digit and 13-digit timestamp?
10 digits are seconds since 1970 (the Unix standard, used by JWT exp); 13 digits are milliseconds (what JavaScript's Date.now() returns). Mixing them is a classic bug: seconds passed to JavaScript yield January 1970, and milliseconds in a JWT exp create a token that effectively never expires. Count the digits before you convert.
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