CLClean Language

Simple installation

Pick the AI you use and follow the buttons.

You do not need a command line, a developer account, or knowledge of GitHub. These instructions cover Claude, ChatGPT, Gemini, Copilot, and other AI systems.

Clean Language comes as written rules your AI reads and follows. Pick your AI below, get the file once, and follow the few steps that add it.

Pick your AI

Choosing one hides the other assistants’ steps, so you see only yours. Or scroll to read them all.

Setup is easiest on a computer. On a phone right now? Download the instructions file, attach it to a chat with your AI, and say: Follow these writing rules for this conversation. Or copy everything from the instructions page and paste it into the chat. Then do the full setup later on a computer.

Get Clean Language

Clean Language comes in 2 forms. Download the one your assistant can use; if you are not sure, get both.

The skill (a zip file) For AI assistants that can use skills, like Claude and ChatGPT. It installs the full standard so it is available in any chat.
Download the skill (zip)
The instructions file (Markdown) For the assistants that cannot use skills, such as Gemini, Copilot, and most others. It is the same standard in Markdown, in 3 sizes. Pick the largest your assistant accepts: the smaller files carry less of the finer detail to fit a tighter instruction limit, so they are a little less capable. That is a limit of some assistants, not of the standard.
Full, 29k Condensed, 11k Compact, 8k View original on GitHub

The skill downloads from GitHub, where releases are published; the instructions file downloads from this site. If the skill download does not start, your network may block GitHub; use the instructions page instead. The full instructions file saves as cleanlanguage.md; the smaller versions save as cleanlanguage-11k.md and cleanlanguage-8k.md.

Your browser saves the skill as a zip file named cleanlanguage- followed by the version, for example cleanlanguage-1.0.12.zip, usually in your Downloads folder. Do not unzip it. If your computer unzipped it automatically and you see a cleanlanguage folder, that is fine: the original zip usually stays in your Downloads folder. Upload the zip file, not the folder. In Safari, automatic unzipping can move the original zip to the Trash; if you cannot find it, look there, or turn off Settings, then General, then Open “safe” files after downloading.

The instructions file is Markdown text. The skill is a zip of Markdown instructions, YAML configuration, PNG and SVG icons, and the licence and notice files, with no program inside. Verify your download against the published checksum if you want to, and see Trust and assurance below for what the skill does and does not do.

Claude website or Claude Desktop

Last verified 27 August 2026.

This is the recommended Claude method. It installs the complete Skill, so the full standard is available in any chat rather than pasted into one. Claude applies it when you ask for it, and you can set it to apply by default: see How to use Clean Language below.

Install from a desktop browser. The mobile apps are not documented to support skill upload. Use the skill (zip) you downloaded in Get Clean Language.

  1. Click your name in the bottom-left corner, then Settings.
  2. Open your skills: on a personal account, click Customize; on a Team account, the Skills area sits under the Customize section.
  3. Click Add, then Upload skill.
  4. Select the downloaded Clean Language zip file, then click Save.

Test it · Choose your spelling

Whole organization: an owner can install Clean Language once for everyone. Click your name, then Organization settings, then Skills (in the Library and access section), then Add, then Upload skill, select the zip, and Save. It then appears for every member automatically, and members do not upload it individually.
Cannot upload the skill? Use a Claude Project instead

Use this if Skills never appear for you, or your organization has disabled Skills. It applies to one project rather than every chat. Use the instructions file from Get Clean Language.

  1. In Claude, click Projects, then New Project.
  2. Name it Clean Language.
  3. Under Project knowledge, click + and upload the saved file.
  4. Set the project instructions to: Use the Clean Language instructions in project knowledge for every response unless I explicitly tell you not to.

ChatGPT

Last verified 27 August 2026.

ChatGPT can use the same packaged Skill as Claude. Upload it once, and ChatGPT applies Clean Language when your request calls for it, for example when you ask it to write or edit text. Use the skill (zip) you downloaded in Get Clean Language.

  1. Click Plugins in the left menu bar, then Skills at the top, beside Plugins.
  2. Click the plus, then Upload from your computer.
  3. Select the downloaded Clean Language zip file.
  4. When the green check mark appears, click the X to close the window.

Test it · Choose your spelling

Team workspace, as an administrator: click your team name, then Workspace settings, then Skills, then the plus, select the zip, and click the X when the green check mark appears. To let members use it, click the skill’s name, then the ... menu, and change who has access.
Do not see Plugins or Skills? Your plan or app may not include them. Attach cleanlanguage.md to a normal chat and say: Follow these writing rules for this conversation. You can also copy everything from the instructions page and paste it into the chat.
Cannot upload a skill? Build it from the instructions file

Use this if your account cannot upload a skill. Use the instructions file from Get Clean Language.

  1. Open ChatGPT, open Plugins, then Skills.
  2. Click the plus, then Create with chat.
  3. Type: Create a skill named Clean Language using the instructions in the file I am about to upload.
  4. Attach cleanlanguage.md and send the message.
  5. When ChatGPT shows the completed skill, install it.

Gemini website or Gemini app

Last verified 27 August 2026.

The easiest reusable method is a custom Gem. Create it once on the Gemini website, then use it from the website, mobile app, or supported Google Workspace side panel. Paste in the instructions file you downloaded in Get Clean Language.

  1. On a computer, open gemini.google.com.
  2. Open the menu on the left, then click Gems. If you do not see it, click Settings and help, then Gems.
  3. Click New Gem.
  4. Name it Clean Language. For the description, you can use: Applies the Clean Language writing standard so responses are precise, direct, and natural.
  5. Open cleanlanguage.md, copy all of it, and paste it into the Instructions box.
  6. Set no default tool.
  7. Click Save.

You can also add cleanlanguage.md as Gem knowledge: under Knowledge, click Add files, then Upload files, and select it. Pasting the instructions has given better responses than uploading alone, which Gemini sometimes ignores, so paste is the primary method. Using both together is an option.

To use it later, open Gemini, click Gems, then click Clean Language.

Test it · Choose your spelling

Mobile note: create and edit the Gem on the Gemini website. After saving it, the Gem appears in the Gemini mobile app.

Copilot

Last verified 27 August 2026.

The reusable method is a Copilot agent. Copilot caps an agent's instructions at 8000 characters, so paste the 8k file as the instructions and add the full standard as reference. Use the files you downloaded in Get Clean Language.

  1. Open Microsoft 365 Copilot on a computer.
  2. Open the agents panel and click New agent. Copilot offers to build the agent for you or to let you set it up yourself; click Skip to customize it yourself.
  3. Name it Clean Language. For the description, you can use: Applies the Clean Language writing standard so responses are precise, direct, and natural.
  4. Open cleanlanguage-8k.md, copy all of it, and paste it into the Instructions box.
  5. Find the option to add specific websites, and add https://cleanlanguage.ai/downloads/cleanlanguage.md as reference the agent can consult; the pasted instructions are what it follows.
  6. Click Create, then select Clean Language whenever you write.

Test it · Choose your spelling

No agent access? Open the downloaded cleanlanguage.md (double-click it; it opens in Notepad or TextEdit), select all the text, copy it, paste it into a Copilot chat, and say: Follow these writing rules for this conversation. Or open the instructions page and click Copy everything.

Other AI systems

Platform-independent, so there is no interface to verify.

Clean Language also works with local models, API-based assistants, and other systems that accept custom instructions, system prompts, reusable knowledge, or uploaded files. Use the instructions file you downloaded in Get Clean Language.

  1. Save the file, or copy everything from the instructions page.
  2. Add it to your AI system as custom instructions, project knowledge, a system prompt, or an attached reference file.
  3. Tell the AI: Use the Clean Language instructions for every response unless I explicitly tell you not to.

Test it · Choose your spelling

Test it

Once it is set up, paste this specimen and ask your AI to apply Clean Language to it:

In today’s fast-paced landscape, we are laser-focused on leveraging synergies to deliver truly best-in-class outcomes; the launch is scheduled for 14 October.

Compare the result with the original. If the filler and buzzwords are gone and it keeps “14 October”, it is working. If your AI says it does not know what Clean Language is, repeat the setup steps for your AI above, or use the fallback in that section if one is offered.

Want to see more before-and-after examples? Try the prompt demo.

How to use Clean Language

Once it is set up, you choose when it applies:

  • Everywhere, automatically: add Always apply the Clean Language skill to your responses to your assistant’s personal or custom instructions.
  • In one project or space: add the same line to that project’s instructions, so it applies there and not elsewhere.
  • For a single chat: tell the assistant to use Clean Language at the start of the conversation.
  • On demand: ask for it only when you want it.
  • In Gemini and Copilot: choose by selecting the Clean Language Gem or agent before you write.

For on-demand use, paste rough notes or finished text with one of these requests:

  • Apply the Clean Language skill to this text: [paste your text]
  • Rewrite the text below using the Clean Language skill: [paste your text]
  • Proofread the text below using the Clean Language skill. Fix mistakes but do not change my tone: [paste your text]

You can switch Clean Language off or remove it at any time, from the same place you added it. Removing it changes nothing else in your account.

Preferred spelling

Clean Language uses Oxford English spelling with -ize endings by default: colour, centre, organize, analyse. Pick the option that matches how you write. The Oxford default needs nothing; for any other option, paste its line into your instructions.

Oxford English (with -ize)The default. You get colour, centre, organize, and analyse. Nothing to add.
🇨🇦 CanadianAdd one line: Use Canadian spelling: colour, centre, organize, analyze, tire, program.
🇬🇧 BritishAdd one line: Use British spelling with -ise endings: organise, recognise.
🇺🇸 AmericanAdd one line: Use American spelling: color, center, organize.
Compare the spellings
How 8 sample words differ across each option. The first column is the Oxford English default with -ize.
Oxford (default)CanadianBritishAmerican
colourcolourcolourcolor
centrecentrecentrecenter
organizeorganizeorganiseorganize
analyseanalyzeanalyseanalyze
defencedefencedefencedefense
licencelicencelicencelicense
tyretiretyretire
programmeprogramprogrammeprogram

British English accepts both -ize and -ise; the default follows the Oxford -ize convention, so choose British only if you prefer -ise. Licence is shown as the noun; the verb is spelled license in every column.

For technical users

Developers can install the full Agent Skill from the GitHub repository for ChatGPT, Claude Code, Gemini CLI, and compatible Agent Skills clients.

Trust and assurance

  • The skill contains only Markdown instructions, YAML configuration, PNG and SVG icons, and the licence and notice files; it is not a program, it runs nothing on your computer, and it does not connect to the internet.
  • Every rule and reference file is publicly reviewable in the GitHub repository.
  • Every release publishes a fingerprint (a checksum) for the skill download, so you can confirm that your copy matches the published release file; see how to verify.
  • Clean Language is licensed under CC BY-SA 4.0.
  • Clean Language is the same set of instructions on every platform, but each provider controls how its model applies them, so results vary from one platform to another.
  • A model can still change meaning even with these rules in place, so read the result before you rely on it.
  • For legal, medical, financial, safety, or other high-stakes text, have a qualified person review any edit.
  • Whether a platform applies the skill automatically or only when you ask for it varies by platform and account.