Custom Domains

Pro plan feature — bring your own domain for tunnel URLs.

Custom domains let you use your own domain instead of *.yourname.nullbore.com. You set up one wildcard CNAME, and all your named tunnels work under it automatically.

How it works

Instead of api.yourname.nullbore.com, your tunnels become api.tunnel.yourcompany.com:

https://api.tunnel.yourcompany.com     → localhost:3000
https://staging.tunnel.yourcompany.com → localhost:8080
https://admin.tunnel.yourcompany.com   → localhost:9090

Setup

1. Add a wildcard CNAME

Point a subdomain and its wildcard to NullBore:

*.tunnel.yourcompany.com   CNAME   tunnel.nullbore.com
  tunnel.yourcompany.com   CNAME   tunnel.nullbore.com

Tip: You can use any subdomain — tunnel., dev., preview., etc. Just make sure both the wildcard and the base record exist.

2. Register in the dashboard

Go to Dashboard → Custom Domains and add your domain (e.g. tunnel.yourcompany.com). NullBore verifies the CNAME and provisions a TLS certificate automatically.

3. Open tunnels

Named tunnels automatically resolve under your custom domain:

nullbore open 3000 --name api
# → https://api.tunnel.yourcompany.com → localhost:3000

No extra flags needed — NullBore routes based on the domain and your account.

Why a subdomain?

You CNAME a subdomain like tunnel.yourcompany.com (not yourcompany.com directly) because:

Wildcard CNAME — one DNS record covers all tunnel names (*.tunnel.yourcompany.com)
No per-tunnel DNS changes — create tunnels freely without touching DNS
No conflict — your main domain, email MX records, etc. are unaffected
Clean separation — tunnel. makes it obvious what the subdomain is for

Self-hosted

On a self-hosted server, add the custom domain to your TLS configuration:

nullbore-server \
  --base-domain tunnel.yourdomain.com \
  --tls-domain tunnel.yourdomain.com,tunnel.yourcompany.com

The server will automatically provision TLS certificates for both domains via Let's Encrypt.

Status: Custom domain support is in active development. The server-side routing and TLS infrastructure are in place. Dashboard UI for domain registration is coming soon.

NullBore Documentation