Your keys are yours. Your content is yours.

What Castwyn stores

• Your email and password hash — to sign you in. Passwords are hashed, never stored in readable form.
• Your AI provider keys — encrypted with AES-256-GCM before they reach the database. They are used only to call the provider you chose, on your behalf.
• Social account tokens — encrypted the same way, used only to publish the posts you approve.
• Your posts, drafts, schedule, and voice settings — the content you create in Castwyn.
• Post performance counts — if you use Insights, only normalized totals (likes, replies, reposts) and the time they were refreshed.

What Castwyn does not do

• We do not sell your data. There is no advertising business here.
• We do not train AI models on your content. Generation runs through your provider account under that provider’s terms.
• We do not store raw responses from social platforms, your followers’ private data, or your audience lists.
• We do not log your API keys, tokens, or the content of your emails.

Who else processes your data

Castwyn runs on a small, deliberate set of subprocessors:

• Vercel — hosting and delivery of the app.
• Supabase — the managed Postgres database.
• Stripe — payments. Card details go directly to Stripe; Castwyn never sees or stores a card number.
• Resend — transactional email such as password resets.
• The AI provider you choose (OpenAI, Anthropic, and any optional media providers you connect) — under your own account and their terms.

Deleting your account

Deletion is self-serve and immediate. In Account & billing, choose Delete account. Castwyn cancels your subscription first, then erases your keys, tokens, posts, schedule, and settings. There is no waiting period and no email required to get it done.

Security practices

• Secrets are encrypted at rest with AES-256-GCM before they touch the database.
• Database access is server-only. Row Level Security is enabled on every application table as a deny-by-default backstop.
• API tokens are hashed at rest, shown to you exactly once, and revocable at any time.
• Two-step sign-in is available: turn it on in Account & billing and signing in also needs a 6-digit code emailed to you, so a stolen password is not enough on its own. Codes are hashed at rest, expire in 10 minutes, and can be used once. You also get single-use recovery codes when you switch it on, so losing access to your inbox does not mean losing your account.
• All traffic is served over HTTPS.

Reporting a problem

If you find a security issue, please report it before disclosing it publicly. Use the support page and mark it as a security report. You will get a response, and credit if you want it.

Castwyn is run by one person. If something here is unclear, ask — a plain answer is better than a long policy.