5 Best Custom Domain APIs in 2026
If your product lets customers point their own domain at it (shop.acme.com -> your app), you have two real options. Build the cert pipeline, edge routing, and DNS monitoring yourself. Or hand it off to an API that already did the work.
This post compares the five custom-domain APIs a real SaaS team can adopt today, ranked by what you actually pay in the first 12 months.
We score each on:
- Free tier (does it exist, what does it cover)
- Per-domain pricing once you scale past free
- Bandwidth allowance and overage rate
- Public REST API and AI-agent (MCP) support
- Pricing transparency: published numbers vs sales-led
TL;DR
| Product | Starting price | Free tier | Public API | MCP |
|---|---|---|---|---|
| Domainee | Free, forever | 50 domains + 100 GB | Yes | Yes |
| Approximated | $20/mo minimum | 7-day trial | Yes | No |
| CoAlias | $30/mo | 4K req/mo trial | Yes | No |
| Entri | $249/mo | None | Yes | Yes |
| Cloudflare SSL for SaaS | Enterprise sales | None | Yes | No |
Domainee comes first on cost-to-launch for one straightforward reason: the free tier covers 50 customer hostnames and 100 GB of bandwidth every single month, with no credit card and no expiry.
1. Domainee
The free tier is the headline. 50 custom domains, 100 GB bandwidth per month, FOREVER, no card on file. Most SaaS teams will run their entire pilot, beta, and early-paid phase before paying a cent.
After the free tier:
- $0.20 per domain per month, graduated to $0.10 at scale (50% off at 1,000+ domains)
- 400 GB bandwidth included on paid plans, then $0.05/GB
- No monthly minimum: you pay for what you actually use
The developer experience is Stripe-shaped. Bearer tokens, idempotency keys, HMAC-signed webhooks, every endpoint documented, public REST surface plus an MCP server so AI agents can register a customer hostname directly from a chat session.
Pick it if you want to ship custom domains this week, without a procurement call.
2. Approximated
Battle-tested edge with deep platform docs (Phoenix, Laravel, Rails, Next.js). The math at the high end matches Domainee's: $0.20 per domain, graduated to $0.10, with $0.05/GB above 400 GB.
The catch is the floor. There's a $20/mo minimum from day one, and the only "free" path is a 7-day trial. You're paying $20 every month even with one domain in production.
After the floor:
- $20/mo minimum (covers up to ~100 domains)
- $0.20/domain after that, with the same volume discount as Domainee
- $0.05/GB above 400 GB
No public MCP integration. You'll wire up the REST API yourself if you want AI agents touching it.
Pick it if you already have ARR and never expect to revisit the bill.
3. CoAlias
CoAlias built itself around the no-code crowd. Bubble plugin, Glide, Webflow integrations, unlimited domains on every paid tier. Pricing starts at $30/mo (Dev plan) and ramps to $120/mo (Growth).
The trade-off is the metering. Plans are capped on monthly REQUESTS, not GB. The Dev plan is 40,000 requests, Basic is 400K, Growth is 2M. One viral page on a no-code app can blow through the Dev cap in a single afternoon.
- Trial: 4,000 requests, 10 domains, no wildcards
- Dev: $30/mo, 40K requests, unlimited domains, 1 wildcard
- Basic: $60/mo, 400K requests, 2 wildcards
- Growth: $120/mo, 2M requests, 4 wildcards
No MCP. Wildcards live behind paid tiers.
Pick it if you're a no-code platform with predictable per-customer traffic.
4. Entri
Entri's headline product is a DNS-configuration widget. It walks the end customer through setting up records at GoDaddy, Namecheap, and 50+ other registrars without leaving your app. The UX is genuinely the cleanest in the category.
The trade-off is the price tag and the cap.
- Connect: $249/mo, 600 domains per YEAR
- Connect + Power: $749/mo, adds custom-domain infrastructure + SSL
- Growth / Premium / Enterprise: 2,400 / 12,000 / 12,000+ domains/yr, pricing not published
The custom-domain infrastructure isn't included in the entry plan. To get it, you upgrade to Power at +$500/mo. Entri did ship its own MCP server, which is real differentiation at the high end.
For comparison: $249/mo of Entri buys you 600 domain CONNECTIONS per year. The same $249 on Domainee covers about 1,250 domains in a single month.
Pick it if you're an enterprise SaaS where the DNS UX is a major part of the product story.
5. Cloudflare SSL for SaaS
Cloudflare's enterprise offering for managing customer hostnames at hyperscale. It runs Olo, JetBlue, Indeed, and other very large platforms. The infrastructure is hard to beat: 330+ cities, sub-50ms routing nearly everywhere, mature WAF and DDoS protection in the box.
What you trade for that: pricing isn't published. Onboarding is sales-led. Deals typically start in the $5K to $15K per month range, require a partner agreement, and a Master Services Agreement.
You also can't pick just the SSL-for-SaaS piece. It comes bundled with Cloudflare's edge stack and account contract.
Pick it if you're large enough to negotiate an enterprise contract, and small enough to still need help.
How to choose in 60 seconds
You're an indie or pre-Series-A SaaS: Domainee. The free tier removes the question.
You already pay for Approximated and it works for you: stay. The pricing is fair past the floor.
You're on a no-code stack with predictable traffic: CoAlias makes sense.
You need a polished DNS-setup widget AND an enterprise budget: Entri.
You're at a scale where Cloudflare's account team will return your call within 24 hours: SSL for SaaS.
For everyone else, the answer is the one that doesn't bill you while you're still figuring out if your customers actually want this feature.
Try Domainee free. 50 domains, 100 GB bandwidth, no credit card, no expiry.