# Bun Hash a password

> Hash a password

- Skill: `jarle/bun-hash-a-password` (Agent Skill)
- Install (CLI): `npx skillmds@latest add jarle/bun-hash-a-password`
- Raw SKILL.md: https://api.skillmd.com/api/skills/jarle/bun-hash-a-password/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: jarle (https://skillmd.com/u/jarle)
- Updated: 2026-09-21
- Page: https://skillmd.com/skills/jarle/bun-hash-a-password

---


# Hash a password

The `Bun.password.hash()` function provides a fast, built-in mechanism for securely hashing passwords in Bun. No third-party dependencies are required.

```ts  theme={"theme":{"light":"github-light","dark":"dracula"}}
const password = "super-secure-pa$$word";

const hash = await Bun.password.hash(password);
// => $argon2id$v=19$m=65536,t=2,p=1$tFq+9AVr1bfPxQdh6E8DQRhEXg/M/...
```

***

By default, this uses the [Argon2id](https://en.wikipedia.org/wiki/Argon2) algorithm. Pass a second argument to `Bun.password.hash()` to use a different algorithm or configure the hashing parameters.

```ts  theme={"theme":{"light":"github-light","dark":"dracula"}}
const password = "super-secure-pa$$word";

// use argon2 (default)
const argonHash = await Bun.password.hash(password, {
  memoryCost: 4, // memory usage in kibibytes
  timeCost: 3, // the number of iterations
});
```

***

Bun also implements the [bcrypt](https://en.wikipedia.org/wiki/Bcrypt) algorithm. Specify `algorithm: "bcrypt"` to use it.

```ts  theme={"theme":{"light":"github-light","dark":"dracula"}}
// use bcrypt
const bcryptHash = await Bun.password.hash(password, {
  algorithm: "bcrypt",
  cost: 4, // number between 4-31
});
```

***

Use `Bun.password.verify()` to verify a password. The algorithm and its parameters are stored in the hash itself, so re-specifying configuration is unnecessary.

```ts  theme={"theme":{"light":"github-light","dark":"dracula"}}
const password = "super-secure-pa$$word";
const hash = await Bun.password.hash(password);

const isMatch = await Bun.password.verify(password, hash);
// => true
```

***

See [Docs > API > Hashing](/runtime/hashing#bun-password) for complete documentation.