Humanizer is a free skill for Claude, built from Wikipedia’s own list of the signs of AI writing. It checks your text for 25 of them and rewrites it without changing what you meant. If a detail is missing, it asks you instead of making one up.
The link: github.com/blader/humanizer. Free and open source (MIT), with 47,000+ stars on GitHub.
What it catches
Five of the 25, the ones you’ll recognize straight away:
| The tell | What it looks like |
|---|---|
| Not X, but Y | “It’s not a tool — it’s a partner.” |
| The one-line closer | “Big ideas. Bigger possibilities.” |
| Dashes everywhere | “Let’s connect — to discuss — next steps.” |
| Forced threes | “Fast, simple, and powerful.” |
| Chatbot leftovers | “I hope this helps! Let me know if you have any questions.” |
đź“‹ Paste this into your AI
Copy this into ChatGPT or Claude and paste an email you’ve written at the bottom. No install needed.
Rewrite the email below so it sounds like I wrote it, not an AI. Keep every fact and exactly what I mean.
Remove these tells: “it’s not X, it’s Y” contrasts, dramatic one-line endings, dashes used as the connector for everything, lists of three that are only there for rhythm, inflated or salesy words, and filler like “I hope this helps.”
Don’t invent anything. If a detail is missing, ask me instead. Keep it the same length or shorter.
Give me the final email only, then one line listing what you changed.
My email: [paste it here]
That’s the quick version. The skill below checks all 25, every time, without the copy-paste.
Set it up in Claude
- Download it. Open github.com/blader/humanizer, click the green Code button, then Download ZIP. Don’t unzip it.
- Turn on code execution. In Claude, go to Settings → Capabilities and make sure code execution is on.
- Upload the skill. Settings → Customize → Skills, click the plus button, choose Create skill, then Upload a skill, and pick the ZIP.
- Use it. Paste your email and type “Humanize this.”
It syncs to Claude’s desktop and mobile apps on the same account. On Claude Code instead? Run /plugin marketplace add blader/humanizer, then /plugin install humanizer@humanizer.
The three traps
- Only download the real one. A skill is a set of instructions Claude follows, so a copycat can tell it anything. The real one is
blader/humanizer. - It gives you three versions. By default you get a draft, a critique and the final. Scroll to the last one, or ask for “the final version only.”
- It doesn’t know your voice yet. Paste two or three paragraphs you wrote yourself first, and it matches them.
Start this week
- Test it. Run the last email you sent through the prompt above. Read both out loud.
- Install it. Four steps, a few minutes, and it’s there every time you write.
- Teach it your voice. Keep one paragraph of your own writing handy and paste it in before anything important.