Synthima Password Generator

Generate cryptographically random passwords using crypto.getRandomValues.

The hosted app is linked from this repo's About section.

Built on top of the JSR library Synthima.

---

Features

• Cryptographically random output via crypto.getRandomValues
• 47 built-in character set presets (Latin, Cyrillic, Greek, Arabic, CJK, and more)
• Simple mode: toggle the four common sets (uppercase, lowercase, numbers, symbols)
• Advanced mode: add any preset or hand-type custom character sets with per-requirement min/max
• Shareable URLs — the full configuration is encoded in the URL and updates live

---

Shareable URLs

Every configuration is encoded in the URL so you can share or bookmark specific setups.

Format: ?length=N&r=<preset>&r=<preset>:<min>&r=<preset>:<min>:<max>

• length — password length (default: 12)
• r — one requirement per param; value is a preset key, optionally followed by :min and :max
• Omit :min when it's 1 (the default); omit :max when there's no upper limit
• Unknown preset keys are treated as raw character strings

Example links

Description	Query
Strong password (16 chars)	uppercase + lowercase + numbers + symbols — /?length=16&r=uppercase&r=lowercase&r=numbers&r=special
6-digit PIN	numbers only — /?length=6&r=numbers
Letters only	uppercase + lowercase, no numbers or symbols — /?length=12&r=uppercase&r=lowercase
Numbers-heavy	at least 4 digits — /?length=16&r=uppercase&r=lowercase&r=numbers:4&r=special
Constrained symbols	max 2 special chars — /?length=16&r=uppercase&r=lowercase&r=numbers&r=special:1:2
Greek + numbers	exotic mix — /?length=20&r=greek&r=numbers
Russian + symbols	Cyrillic with special chars — /?length=24&r=russian&r=numbers&r=special

Preset keys

Key	Characters
uppercase	A–Z
lowercase	a–z
numbers	0–9
special	!@#$%^&*
german-upper / german-lower	Base Latin + ÄÖÜ / äöüß
french-upper / french-lower	Base Latin + French diacritics
spanish	Base Latin + ñÑ¿¡
nordic-upper / nordic-lower	Base Latin + ÅÆØÐÞ / åæøðþ
central-eu-upper / central-eu-lower	Base Latin + Central European
romanian-upper / romanian-lower	Base Latin + ĂÂÎȘȚ / ăâîșț
turkish-upper / turkish-lower	Base Latin + ÇĞİŞÖÜ / çğışöü
portuguese-upper / portuguese-lower	Base Latin + Portuguese diacritics
latin-extended	Full Latin Extended block
extended-special	£€¥₹ ± × ÷ ≠ ≈ ∞ … and more
currency	£ € ¥ ₹ ₽ ₩ ₪ ₿ ¢
math	± × ÷ ≠ ≈ ∞ ∑ ∏ √ ∫ ∂
arrows	← → ↑ ↓ ↔ ↗ ↘ ↙ ↖ ⇒ ⇐ ⇑ ⇓
typographic	« » „ " " ' ' … † ‡ § ¶ •
superscripts / subscripts	⁰¹²³… / ₀₁₂₃…
russian	Full Russian Cyrillic
ukrainian	Full Ukrainian Cyrillic
bulgarian	Full Bulgarian Cyrillic
serbian-cyrillic	Full Serbian Cyrillic
greek	Full Greek alphabet
arabic-letters	Arabic consonants
arabic-indic	Arabic-Indic digits ٠١٢…
arabic-punct	، ؛ ؟
hebrew-letters	Hebrew alphabet
hindi-consonants / hindi-vowels	Devanagari consonants / vowels
cjk	3500 common CJK characters
hiragana	Japanese Hiragana
katakana	Japanese Katakana
korean-consonants / korean-vowels	Korean Jamo
georgian	Georgian Mkhedruli
armenian	Armenian alphabet
thai-consonants / thai-vowels	Thai consonants / vowels

---

REST API

Generate passwords programmatically via GET /api/generate.

Path: /api/generate on the hosted app (or http://localhost:5173 in dev)

Parameters

Param	Default	Description
length	12	Password length (integer ≥ 1)
r	—	Charset requirement — repeatable; same format as URL params above
count	1	Number of passwords to return (integer 1–100)
format	json	json → JSON array, csv → one password per line

Examples

# One password, default settings
curl "https://<host>/api/generate"
# ["M#0DpNE7c45&"]

# 5 strong passwords, 16 chars
curl "https://<host>/api/generate?length=16&r=uppercase&r=lowercase&r=numbers&r=special&count=5"

# 10 PINs as plain text (one per line)
curl "https://<host>/api/generate?length=6&r=numbers&count=10&format=csv"

Errors

Invalid parameters return 400 with a JSON error body:

{ "error": "count must be between 1 and 100" }
{ "error": "format must be json or csv" }
{ "error": "length must be between 1 and 256" }

---

MCP server

The generator is also available as a Model Context Protocol server, so MCP clients (Claude Desktop, Claude Code, etc.) can generate passwords directly. It exposes two tools:

Tool	Arguments	Returns
generate_password	length (1–256, default 12), count (1–100, default 1), requirements (optional array — see below)	The generated password(s), one per line
list_charset_presets	none	Every preset as { key, name, size, sample }

Each requirements item is either a preset key or a literal charSet, with optional min/max occurrence counts. With no requirements, passwords use a strong default mix of uppercase, lowercase, numbers, and special characters.

// example generate_password arguments
{
  "length": 20,
  "count": 3,
  "requirements": [
    { "preset": "uppercase", "min": 2 },
    { "preset": "numbers", "min": 2 },
    { "charSet": "!@#$", "max": 4 }
  ]
}

Remote endpoint (hosted)

Streamable HTTP at POST /mcp — no install required, just add the URL:

claude mcp add --transport http password-gen https://<host>/mcp

In Claude Desktop / Claude.ai: Settings → Connectors → Add custom connector and paste https://<host>/mcp.

Local (stdio)

Runs on your machine over stdio — nothing leaves the process. Requires Deno v2+ and a checkout of this repo:

claude mcp add password-gen -- deno run -A /absolute/path/to/synthima-web/mcp/stdio.ts

Or configure it directly in your client:

{
  "mcpServers": {
    "password-gen": {
      "command": "deno",
      "args": ["run", "-A", "mcp/stdio.ts"],
      "cwd": "/absolute/path/to/synthima-web"
    }
  }
}

Both transports are thin wrappers over the same generator core as the web app and REST API.

Protocol revision

Both transports speak the 2026-07-28 revision, which is stateless: no initialize handshake and no session id, so every request stands alone and the server holds nothing between calls — long-lived subscription streams are refused outright, since nothing here is subscribable.

Only that revision is served. Clients speaking the older 2025-era protocol are turned away at connect rather than silently downgraded, so make sure yours is recent enough.

---

Setup

Prerequisites: Deno v2+

# Clone the repo
git clone https://github.com/JakeAve/synthima-web.git
cd synthima-web

# Install git hooks (runs fmt, lint, type-check, and tests on push)
deno task install:githooks

# Start the dev server
deno task dev

The app will be available at http://localhost:5173/.

Available tasks

Command	What it does
deno task dev	Start Vite dev server with HMR
deno task build	Build for production into _fresh/
deno task start	Serve the production build
deno task check	Run formatter check, lint, and type-check
deno task test	Run the unit tests (lib/, routes/)
deno task test:e2e	Build, then run the stdio + HTTP end-to-end tests

Tech stack

• Fresh 2 — Deno-native web framework
• Preact + @preact/signals — UI and reactive state
• Tailwind CSS v4 — Styling
• Synthima — Password generation library
• Vite — Build tooling