Reusable blocks. Dynamic prompts.

Build your best prompts once. Use them in every AI tool.

PromptMason is a private prompt library. Build prompts from reusable blocks, keep them encrypted on your own computer and share them with the people you choose. Built-in MCP plugs your library into Claude, Cursor and your other AI apps, and Built-in Private AI runs a free AI model right on your computer, so private work never leaves it.

Try Pro free for 14 daysSee pricing

Just your email, no card, no account.

  • No account
  • Nothing stored on our servers
  • Encrypted on your computer
  • No tracking
The Build screen: a list of blocks on the left, three blocks arranged on the canvas, and the finished prompt in the preview on the right.The Build screen: a list of blocks on the left, three blocks arranged on the canvas, and the finished prompt in the preview on the right.
Drag blocks onto the canvas and see the finished prompt as you go.
Settings, AI & connected apps: what connected apps can do (full access, read-only or off), and Claude Desktop, Cursor and Claude Code ready to add.Settings, AI & connected apps: what connected apps can do (full access, read-only or off), and Claude Desktop, Cursor and Claude Code ready to add.
Built-in MCP plugs your library into Claude, Cursor and your other AI apps.
Chat on the local model, marked “Private: this chat stays on this computer”, with a three-point answer.Chat on the local model, marked “Private: this chat stays on this computer”, with a three-point answer.
Built-in Private AI: chat with a free AI model that runs on your computer. Nothing you write leaves it.
A block being edited, with AI assist’s suggested rewrite under it and the changes marked line by line, ready to accept or discard.A block being edited, with AI assist’s suggested rewrite under it and the changes marked line by line, ready to accept or discard.
AI assist rewrites a block while you edit, and shows exactly what it changed.
A prompt with its Evaluate grade: a score of 7 out of 10, what works, and what to improve in the task, constraints and format.A prompt with its Evaluate grade: a score of 7 out of 10, what works, and what to improve in the task, constraints and format.
Evaluate grades a prompt out of 10 and tells you what to improve.
The PromptMason Chrome extension open from Chrome’s toolbar over a web page: search and folders at the top, a list of prompts, and the chosen prompt ready to copy.The PromptMason Chrome extension open from Chrome’s toolbar over a web page: search and folders at the top, a list of prompts, and the chosen prompt ready to copy.
The Chrome extension: open your library from Chrome’s toolbar on any website and copy a prompt, ready to send.
The Manage window of a team library called Acme Corp: the invite to send, and its members with their roles and PCs.The Manage window of a team library called Acme Corp: the invite to send, and its members with their roles and PCs.
Share a library with your team. Only the people you invite can read it.
Home with Quick Launch, the library’s counts, and a graph of how its blocks and prompts connect.Home with Quick Launch, the library’s counts, and a graph of how its blocks and prompts connect.
See your whole library at a glance, and how every block and prompt connects.
Home with a chart of which blocks are used in which prompts.Home with a chart of which blocks are used in which prompts.
See which blocks feed which prompts before you change one.
A Markdown document being edited: an AI Skill for weekly status updates, with Copy and Download .md.A Markdown document being edited: an AI Skill for weekly status updates, with Copy and Download .md.
Keep AI Skills and Markdown documents next to your prompts.

Stop rewriting the same prompts

Your best prompts share the same pieces. PromptMason turns those pieces into blocks, so every prompt starts from your best work.

Write a block once

A block is one reusable piece of a prompt: a role, background about your work, a task, a format, a rule. Save it once and use it in as many prompts as you like.

Drag blocks into a prompt

Build a prompt by dragging blocks onto the canvas and putting them in order. See the finished prompt as you go.

Improve it everywhere at once

Change a block and every dynamic prompt that uses it is updated. No hunting through old documents for the version that worked.

Start with 4 starter packs

59 carefully written blocks and 16 prompts, with the variables already set up. Add a pack in a click, then make it your own. No blank page.

See the prompt library

  • Starter pack · 20 blocks, 4 prompts
  • Finance pack · 13 blocks, 4 prompts
  • Legal pack · 13 blocks, 4 prompts
  • Marketing pack · 13 blocks, 4 prompts

Everything's built in

Your library connects to the AI tools you use, with nothing extra to pay for.

Built-in MCP

One click connects Claude Desktop or Cursor, and one command connects Claude Code. Your AI app finds your prompts, fills them in and saves new ones, with the access you choose.

Learn more

Built-in Private AI

A free AI model that runs on your computer. No API key, no account, no internet connection needed, and none of your text leaves your computer.

Learn more

Chat, built in

Run your saved prompts in a conversation with the free model, or with your own OpenAI, Anthropic, Google Gemini or xAI key.

Claude, ChatGPT, Gemini and Copilot in tabs

Open the AI sites you already use inside PromptMason, signed in to your own account, and drop a saved prompt straight into the message box.

Chrome extension

An extension for the Chrome browser. Open your library from Chrome’s toolbar on any website, pick a prompt and paste it into any chat box.

Learn more

Markdown documents and Skills

Keep AI Skills and Markdown documents next to your prompts, preview them formatted, and download them as .md files.

Fill-in-the-blanks prompts

Save your company name once and use it everywhere, or have PromptMason ask for the topic or deadline each time you copy.

AI assist and Evaluate

AI assist rewrites a block while you edit. Evaluate grades a prompt out of 10 and tells you what to improve.

Private by design

Your prompts hold your know-how and private information. With PromptMason, they stay with you.

  • Your library lives on your computer, encrypted. No account, nothing kept on our servers, no tracking.
  • Use the free built-in AI model for private work: it works offline, and your text never leaves your computer.
  • Run a privacy check on any prompt to spot personal, financial or confidential details before you paste it into a public AI.
  • You decide what each AI app can do with your library: full access, read-only, or off.

Share with your team

Give coworkers, friends or family the same prompts, always up to date. No new account, no new server: a team library syncs through the cloud folder you already use.

  • Share through OneDrive, SharePoint, Google Drive, Dropbox or a network drive you already use.
  • Only the people you invite can read it. It’s encrypted, every change is signed, and you approve every computer that joins.
  • Improve a prompt once and everyone has the new version. Your own library stays private alongside it.

More about team libraries

The Invite people window for a team library called Acme Corp, with the invite to send and the steps to approve each person.The Invite people window for a team library called Acme Corp, with the invite to send and the steps to approve each person.

One plan with everything

Every feature is in Free, with room for 25 blocks and 15 prompts. Pro removes the limit, so your library can grow with your work. No tiers, no add-ons.

Free

$0 forever

Every feature, for a smaller library.

Pro · Launch offer, save 22%

Normally $7.42$5.75/month*

*Requires an annual subscription: $69 billed once a year. Or $7 billed monthly. The launch price is yours for as long as you stay subscribed.

Every download starts with 14 days of Pro, free. See pricing for the details.

Your best prompts, ready in seconds

Download PromptMason and get 14 days of Pro with no limits. Just your email, no card, no account.

Try Pro free for 14 days

For Windows. Mac and Linux versions are coming soon.