Generators & Utilities — UUIDs, Passwords, Hashes & Cron
Generators and converters for the values you need constantly and should never have to fetch from a server.
9 tools · Reviewed by Mimamsa, Founder & Engineer, CodeLint.Dev
Every tool in this group produces or transforms a value locally, and for several of them that is a hard security requirement rather than a preference. A password generated on a remote server has, by definition, existed somewhere outside your control. A hash computed by uploading the file has meant uploading the file.
The generators use the browser’s own cryptographic primitives — crypto.getRandomValues for random UUIDs and passwords, SubtleCrypto for SHA hashes — rather than JavaScript’s Math.random, which is fast, predictable, and completely unsuitable for anything security-related.
The converters cover the everyday translations: colours between hex, RGB, HSL and OKLCH; physical units across length, mass, temperature and data; images between formats with quality control. Cron expressions get a builder that renders the schedule back to you in plain English, because the difference between a job running monthly and every minute is one character in a five-field string.
Generators
Converters & calculators
Choosing a UUID version
The three versions solve different problems and are not interchangeable:
| Version | Ordering | Use when |
|---|---|---|
| v4 (random) | None — fully random | You need an opaque identifier and ordering is irrelevant: session tokens, correlation IDs, external references |
| v7 (time-ordered) | Lexicographically sortable by creation time | It is a database primary key. The timestamp prefix keeps B-tree inserts local instead of scattering them across the index |
| v1 (timestamp + node) | Sortable, but with the time bytes in an awkward order | You need compatibility with an existing v1 system. For new work v7 supersedes it |
In-depth guides
Long-form articles covering the standards and formulas behind these tools.
- Logical Qubits Arrived: The Honest State of Quantum Computing in 2026 10 min read August 25, 2026
- Passkeys vs Passwords in 2026: How Passkeys Work, Why They Win — and Why You Still Need Strong Passwords 10 min read August 3, 2026
- Cron Expressions Explained: The Complete Guide (Including the DST Bug That Will Eventually Bite You) 9 min read July 16, 2026
- SHA Hash Generator: The Complete Guide to Cryptographic Hashing, File Integrity, and HMAC 10 min read July 14, 2026
- UUID Complete Guide: Versions, Structure, Database Keys, and When to Use Each 10 min read July 13, 2026
Frequently asked questions
- Are the generated passwords and UUIDs actually random?
- They use crypto.getRandomValues(), the browser’s cryptographically secure random number generator, which draws from the operating system’s entropy pool. This is the same primitive a password manager uses. Math.random() is never used for generated values — it is fast but predictable, and unsuitable for anything security-related.
- Should I still use MD5 or SHA-1 for anything?
- Only for non-security work such as detecting accidental file corruption or as a cache key. Both are cryptographically broken: practical collision attacks exist against MD5 and against SHA-1. For signatures, password storage, or anything an attacker has reason to forge, use SHA-256 or better — and for passwords specifically, a purpose-built KDF such as Argon2 or bcrypt rather than a bare hash.
- Is my image uploaded when I convert it?
- No. The file is decoded onto a canvas and re-encoded entirely within your browser using the same codecs the browser uses to display images. The file never leaves your device, which is why conversion also works offline.
- How much password entropy is enough?
- Entropy in bits is what matters, not length or "complexity rules". Roughly: under 50 bits is weak, 60–80 bits is reasonable for an account behind rate limiting, and 100+ bits is appropriate for a key or anything that could be attacked offline. The generator shows the figure live as you adjust length and character set.