Castwyn
AI content engineBring your own key
Use your own AI provider key
You bring your own key. Castwyn writes in your voice with that key. Your provider bills the usage. Castwyn does not add an AI markup.
Supported providers
One key is enough. These are the providers Castwyn can use to write posts:
- OpenAI
- Anthropic
- xAI (Grok)
Your keys are encrypted at rest and used only for your generations.
Subscription sign-in (using a ChatGPT, Claude or Grok subscription instead of an API key) is not available yet. An API key is needed for now.
What Castwyn writes
Castwyn writes posts for 13 networks. LinkedIn, Bluesky, Mastodon, Telegram and Discord publish automatically. Threads and Reddit publishing is not open to everyone yet, so they are copy and paste for now. X publishes only with your own X API keys. The rest are one-click copy and paste.