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Add a custom domain

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Point a domain you own at a Lessly app, with automatic TLS.

Problem

You want your app served on your own domain — like docs.example.com — instead of the generated *.lessly.run URL, with a TLS certificate handled for you.

UI

1. In app.lessly.com, open your service’s domain settings and add the hostname (for example, docs.example.com).
2. Lessly shows two DNS records: a CNAME that points the hostname at Lessly, and a TXT that proves you own it.
3. Add both at your DNS provider. Add the CNAME as DNS-only — if your provider proxies traffic (for example, Cloudflare’s orange cloud), turn the proxy off for this record.
4. Click Verify. Lessly checks the records and issues a TLS certificate.
5. When the certificate is active, your app serves on the domain over HTTPS.

MCP

The same flow through the Lessly MCP server in your agent. Token scope: a key with write access to the app’s domains.

Ask in plain language:

“Add docs.example.com to my app.”

Your agent calls deployment_domain_add and returns the CNAME and TXT records to publish. Add them at your DNS provider (the CNAME as DNS-only), then:

“Verify docs.example.com.”

The agent confirms the records and starts certificate issuance.

Verify it works

1. The domain reports verified, then the certificate moves to active.
2. Open https://docs.example.com — it serves your app with a valid certificate for that hostname.

Certificate issuance takes a few minutes, and up to ~30 minutes the first time. Until the certificate is active the domain may not answer over HTTPS — that is expected, not a failure.

Variations

Migrating a domain that is already live (for example, behind Cloudflare or another CDN). Add the Lessly CNAME as DNS-only, then wait until the hostname resolves to Lessly from a couple of public resolvers before you verify. If you verify while the old proxied record is still cached, certificate issuance can stall — validation needs the domain to resolve to Lessly cleanly. Wait for clean resolution, then verify.

Apex domains. A bare apex such as example.com can’t take a CNAME, so Lessly returns A records for the apex instead — add those and verify the same way as a subdomain. If you’d rather serve on www. and forward the apex there, Lessly can also set up an apex → www redirect for you.