Caddy alternative for SaaS custom domains
An evidence-based comparison of Caddy and subdomain.to for connecting customer-owned domains, managing certificates and routing HTTPS traffic.
Reviewed · Sources checked against first-party documentation
Is subdomain.to a good Caddy alternative?
Yes, when the job is specifically to connect customer-owned domains to an existing SaaS application. Caddy is the best fit when self-hosting, configuration control and open-source infrastructure are requirements. Its On-Demand TLS can ask an application whether a hostname is authorized before issuing a certificate. subdomain.to is the managed alternative when the team does not want to operate the proxy, ACME storage, scaling, monitoring and recovery itself. Caddy is an open-source web server and reverse proxy with automatic HTTPS. On-Demand TLS can obtain a certificate during a TLS handshake after an ask endpoint authorizes the hostname, a pattern explicitly documented for custom-domain SaaS products.
The products are not identical. This page compares only the overlapping custom-domain job; it does not score unrelated hosting, CDN, registrar or infrastructure features as if they were interchangeable.
Caddy vs subdomain.to
“Different” is not automatically worse. The right choice depends on whether you need a broader platform, direct infrastructure control or a focused custom-domain layer.
Product and pricing information reviewed July 30, 2026. Confirm current contractual terms with each vendor before purchasing.
Caddy in three verifiable facts
The comparison uses public, first-party material rather than review-site scores or inferred capabilities.
License model
Open-source server
Certificate mode
Automatic HTTPS and On-Demand TLS
Safety control
Required ask authorization endpoint
Compare the cost boundary, not one headline number.
There is no per-domain software subscription for the open-source server. Compute, bandwidth, storage, observability, on-call and implementation remain your responsibility.
For a fair total-cost comparison, include implementation time, bandwidth or compute, certificate recovery, monitoring, support tooling and the cost of changing providers later. See the build-versus-buy model.
Where Caddy is strong
Caddy is an open-source web server and reverse proxy with automatic HTTPS. On-Demand TLS can obtain a certificate during a TLS handshake after an ask endpoint authorizes the hostname, a pattern explicitly documented for custom-domain SaaS products.
- Open-source and deployable on infrastructure you control.
- Automatic HTTPS and a documented On-Demand TLS authorization pattern.
- Flexible reverse-proxy configuration and JSON admin API.
- No vendor-specific per-domain subscription.
What your team still owns
These are scope differences to evaluate, not claims that the competitor is unsuitable.
- 01Your team owns high availability, scaling, upgrades and incident response.
- 02The ask endpoint, abuse prevention and approved-host inventory must be designed safely.
- 03Product lifecycle states, DNS polling, widgets and webhook delivery are not provided as a SaaS control plane.
Choose from your operating constraints
A useful comparison names the conditions under which either product wins.
Choose Caddy when…
- Self-hosting and complete proxy control are non-negotiable.
- You already operate a reliable edge and certificate platform.
- Your custom routing requirements exceed a managed HTTPS-origin boundary.
Choose subdomain.to when…
- Custom-domain infrastructure is not a core differentiator.
- You want DNS, certificate and routing statuses without building a control plane.
- Your team prefers a subscription to owning edge on-call and renewal recovery.
Moving from Caddy without a DNS cliff
Run both paths during the transition. A domain move combines DNS propagation, certificate readiness and application routing; deleting the old route first removes your safest rollback.
- 01
Inventory
Export every approved hostname, upstream mapping and certificate status from the Caddy control path.
- 02
Prepare
Create equivalent destinations and exact domain resources while Caddy continues serving production.
- 03
Cut over
Move DNS gradually, watch forwarded-host tenant mapping and keep Caddy available until all certificate and routing states are active.
How this comparison was produced
subdomain.to publishes this page and is therefore not a neutral review marketplace. We compare the shared customer-domain workflow, acknowledge where Caddy is stronger, cite first-party product documentation and avoid ratings we did not collect. subdomain.to claims are checked against the implemented application and public pricing page.
We review pricing, scope and source links quarterly or after a material product announcement. If a public fact cannot be verified, it is described as plan-dependent or omitted. Send corrections to hello@subdomain.to.
Caddy alternative FAQ
Short answers for engineering, product and procurement teams.
Can Caddy safely issue certificates for arbitrary customer domains?
Caddy documents On-Demand TLS with an ask endpoint that must authorize a hostname before issuance. The authorization service and abuse controls are your responsibility.
Is Caddy really free?
The open-source server has no per-domain subscription, but production compute, bandwidth, storage, monitoring, maintenance and on-call work still have costs.
What does subdomain.to replace in a Caddy build?
It replaces much of the domain control plane and managed edge operation: DNS checks, certificate lifecycle, registered-host routing, state APIs, widget and signed webhooks.
How current is this comparison?
It was last reviewed on July 30, 2026 against the official product and documentation links above. Vendor plans and features can change, so verify contractual details before purchase.