Humanly

A Chrome extension that rewrites your Gmail drafts to sound human, with three intensity levels (Subtle / Human / CEO). Functionally a Sinceerly clone, BYOK only - bring your own API key, no paid tier, no servers.

What it does

• Adds a ✶ Humanize button to any Gmail compose window.
• Opens a panel with a 3-stop slider (Subtle / Human / CEO) and a Humanize button.
• Calls your chosen AI provider with your key to rewrite the draft.
• Shows the rewritten version with yellow highlights on every change.
• One click replaces your draft.

Supported providers

Provider	Notes	Get a key
Anthropic (Claude)	claude-haiku-4-5 / sonnet-4-6 / opus-4-7	https://console.anthropic.com/settings/keys
OpenAI (GPT)	gpt-4o-mini / gpt-4o / gpt-4.1 / gpt-5	https://platform.openai.com/api-keys
Google Gemini	gemini-2.5-flash / gemini-2.5-pro / gemini-2.0-flash	https://aistudio.google.com/app/apikey
xAI (Grok)	grok-4 / grok-3 / grok-3-mini	https://console.x.ai/
Groq	llama-3.3-70b-versatile / llama-3.1-8b-instant	https://console.groq.com/keys
DeepSeek	deepseek-chat / deepseek-reasoner	https://platform.deepseek.com/api_keys
Mistral	mistral-small-latest / mistral-large-latest	https://console.mistral.ai/api-keys/
OpenRouter	any model on OpenRouter (provider/model format)	https://openrouter.ai/keys

Each provider keeps its own API key — switching back doesn't lose anything. The model field accepts any model ID the provider supports (the dropdown is suggestions, not a closed list).

The three levels

Level	Behavior
Subtle	Removes em-dashes and AI cliches, adds contractions, light edits. Stays professional.
Human	~50% shorter. Casual. Drops formal openers/closers. One or two short paragraphs.
CEO	Aggressively short. Fragments. Lowercase starts. One small typo per ~50 words. Appends "Sent from my iPhone".

Install (load unpacked)

1. Open chrome://extensions in Chrome.
2. Toggle Developer mode on (top right).
3. Click Load unpacked.
4. Select the extension folder (the humanly folder in this repo).
5. Click the Humanly toolbar icon to open settings.
6. Pick a provider, paste your API key, pick a model, click Test key, then Save.
7. Open Gmail, start a draft, click ✶ Humanize.

Install from a release (zip)

1. Download the latest release zip (for example humanly-v1.0.0.zip) from the project's Releases page.
2. Unzip the archive to a folder (e.g. humanly/) somewhere on your machine.
3. Open chrome://extensions in Chrome and enable Developer mode.
4. Click Load unpacked and select the unzipped humanly folder.
5. If you already have Humanly installed in Chrome, you can skip re-loading; otherwise the extension will appear in your list.

Note: if the extension is already installed and working, you don't need to re-download or re-load it.

Privacy

• API keys are stored in chrome.storage.local — local to this browser, nowhere else.
• Email text is sent only to the provider you picked, over HTTPS, only when you click Humanize.
• No analytics, no telemetry, no remote logging. The extension has zero servers.

Files

manifest.json              MV3 manifest with host permissions for all providers
icons/                     16/48/128 PNG action icons
src/
  providers.js             Provider definitions + call functions (one place to add more)
  background.js            Service worker — routes humanize requests through providers
  content.js               Gmail injection, compose detection, slider panel, word-level diff
  content.css              Panel + trigger button styles
  options.html / .css / .js  Settings page (provider + per-provider key + model picker + test)

Adding a new provider

Edit src/providers.js:

1. Add an entry to the PROVIDERS object with label, keyPlaceholder, keyHelpUrl, models, defaultModel, and call.
2. For OpenAI-compatible APIs use makeOpenAILike("https://your-base-url/v1").
3. Add the provider's host to host_permissions in manifest.json.
4. Add the provider id to PROVIDER_ORDER.
5. Reload the extension at chrome://extensions.

Notes

• Default provider is Anthropic; default model is claude-haiku-4-5-20251001 (fast and cheap).
• The Anthropic API requires the anthropic-dangerous-direct-browser-access: true header when called directly from a browser; this extension sets it automatically.
• Gmail's DOM changes occasionally; if the Humanize button stops appearing, check the selectors in getComposeBody() in src/content.js.