LetterBucket includes a built-in AI writing assistant inside the editor. By default, it uses LetterBucket’s own AI (available on paid plans). If you prefer to use your own AI provider, you can connect your API keys under Settings → Advanced → AI Providers.
Supported providers
| Provider | Available models |
|---|
| OpenAI | GPT-5.5, GPT-5.5 Pro, GPT-5.4, GPT-5.4 Mini, GPT-5.4 Nano |
| Anthropic | Claude 4.7 Opus, Claude 4.6 Sonnet, Claude 4.5 Haiku |
| Gemini | Gemini 2.5 Pro, 2.5 Flash, 2.5 Flash Lite, Pro Latest, Flash Latest |
| DeepSeek | DeepSeek Chat, DeepSeek Reasoner |
| Grok | Grok 4, Grok 4 Fast, Grok 3, Grok 3 Mini |
| OpenRouter | All models available through OpenRouter |
Adding a provider
- Go to Settings → Advanced.
- In the AI Providers section, click Add new.
- Select your provider from the list.
- Paste your API key.
- Save — a model selection modal will open automatically so you can choose which model to use.
Once connected, the AI assistant in the editor will use your key and model instead of the built-in one.
Using the AI assistant in the editor
With a provider connected, you can access AI assistance directly while writing:
- Select any text and use the AI actions in the toolbar.
- Use the
/ insert menu to trigger AI-powered content generation.
- The assistant can help you rewrite, expand, summarize, or improve selected content.
LetterBucket’s built-in AI
If you don’t have your own API keys, you can use LetterBucket’s built-in AI by upgrading your plan. No configuration needed — it works out of the box once active.
Using your own API key gives you full control over the model and cost. OpenRouter is a good option if you want to access many different models through a single key.
Managing and removing providers
In the AI Providers list, each connected provider shows its name and configured model. You can:
- Edit — update the API key or switch to a different model.
- Delete — remove the provider. The editor will fall back to LetterBucket’s built-in AI if available on your plan.
