5 Best Custom Domain APIs (Compared by Real Cost to Ship)
The best custom domain API for a SaaS is the one that ships the feature at the cost and control you need. For most teams pre-scale that's Domainee (50 domains and 100 GB free, then $0.20 each). For a large fleet already on Cloudflare it's SSL for SaaS ($0.10 per hostname). This post prices all five through the same three scenarios so you can see where each one wins.
If your product lets customers point their own domain at it (shop.acme.com to your app), you have two real options: build the certificate pipeline, edge routing, and DNS monitoring yourself, or hand it to an API that already did the work. Assuming you'd rather ship, here are the five APIs a SaaS team can adopt today without a sales call, ranked by what they actually cost in year one.
How we evaluated these
I build Domainee, which is one of the five, so the fair way to do this is to show the math and let the numbers argue. Every price below is from each provider's public pricing page, checked in July 2026. Where a provider hides a number (bandwidth, higher tiers), I say so instead of guessing, because an unpriced line is itself a finding.
Five things decide the ranking:
- Free tier: does one exist, and what does it actually cover
- Per-domain rate once you're past free
- Bandwidth allowance and overage rate (the half of the bill people forget)
- Public REST API and AI-agent (MCP) support
- Pricing transparency: published numbers vs "contact sales"
TL;DR
| Product | Starting price | Free tier | Bandwidth | Public API | MCP |
|---|---|---|---|---|---|
| Domainee | Free, forever | 50 domains + 100 GB | 100 GB free, then $0.05/GB | Yes | Yes |
| Approximated | $20/mo minimum | 7-day trial | 400 GB, then $0.05/GB | Yes | No |
| CoAlias | $30/mo | 4K req/mo trial | Metered by requests, not GB | Yes | No |
| Entri | $249/mo | None | Not published | Yes | Yes |
| Cloudflare SSL for SaaS | $0 (100 hostnames) | 100 hostnames included | Your own Cloudflare plan | 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 month, with no credit card and no expiry. But "best" depends on your scale, which is what the cost table further down is for.
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
Domainee is a custom domains API for SaaS with a native MCP server — 50 domains and 100 GB free.
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. I did the full break-even math in Approximated alternative in 2026.
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. I did the full page-view arithmetic in CoAlias alternatives in 2026.
- 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.
The hostname pricing is actually reasonable and public: 100 custom hostnames included on Free, Pro, and Business, then $0.10 per hostname per month up to a 50,000 pay-as-you-go cap. Past that cap it's an Enterprise contract with unpublished pricing.
What you trade is engineering time, not money. Before your first customer you enable custom hostnames on the zone, configure a fallback origin, pick a CNAME target, and choose between three SSL validation methods. Per customer it's an API call plus a polling loop, because hostname webhooks are Enterprise-only. The full walkthrough, with both tutorials side by side, is in the Cloudflare SSL for SaaS setup guide.
Pick it if you already run Cloudflare's edge stack, or you're at a scale where $0.10 flat beats a graduated curve.
Also worth a look: SaaS Custom Domains, SaaSKevin, and DIY on Vercel
SaaS Custom Domains is packaged much like Approximated: a $20/mo minimum covering up to 100 hostnames, $0.20 per domain after, plus API, webhooks, analytics, and a bundled WAF. The gap is that bandwidth allowances and overage rates aren't published, which makes the traffic half of the bill impossible to model up front. The arithmetic is in SaaS Custom Domains alternatives in 2026.
SaaSKevin is the price outlier: 3 domains free, then a flat $0.15/domain/mo, which is the only rate in this market cheaper than ours. It stays off the main list because there's no public API documented and bandwidth is an unpublished "fair use" policy, but if you run a fleet by hand, the sticker is real. The exact crossover math (191 domains) is in SaaSKevin alternatives in 2026.
Building it yourself on Vercel is the path teams weigh before any of these. Vercel charges $0 per custom domain and the Platforms Starter Kit is open source, but the kit ships subdomain tenancy only; verification, cert edge cases, monitoring, and your own API are the real bill. That ledger is itemized in our Vercel Platforms Starter Kit breakdown.
The part nobody puts side by side: what you actually pay
Feature tables are easy to fudge, so here's the real test. Same three scenarios, priced through every provider. Domain cost only, at list prices, ignoring bandwidth (which only Domainee, Approximated, and Cloudflare publish anyway).
| Customer domains | Domainee | Approximated | CoAlias | Entri | Cloudflare | SaaS Custom Domains |
|---|---|---|---|---|---|---|
| 25 | $0 | $20 | $30 | $749 | $0 | $20 |
| 100 | $10 | $20 | $30+ | $749 | $0 | $20 |
| 500 | $90 | $100 | $60-120 | $749 | $40 | $100 |
How to read that:
Below 50 domains, Domainee and Cloudflare are both $0, and everyone else is charging you a floor. The difference is what the $0 costs you elsewhere: Cloudflare's zero is real on the hostname line, but you pay it back in setup (fallback origin, DCV method, a polling loop) and Enterprise-gated webhooks. Domainee's zero comes with webhooks and an MCP server on the free tier.
At 100 domains the field compresses to $10-30 for the self-serve APIs, except Entri, which needs the $749 Power plan before it issues a single certificate, and Cloudflare, still inside its 100 included hostnames.
At 500 domains Cloudflare's flat $0.10 finally wins the raw number at $40, Domainee is next at $90, and the $20-floor products land near $100. CoAlias is a range because it meters requests, not domains, so your bill depends on traffic rather than headcount. If you're deciding at this scale, the tiebreakers stop being price and start being setup time, webhooks, and whether an agent can drive it.
Want to run your own numbers, including bandwidth? The custom domain cost calculator does the full arithmetic, and the complete provider list lives at /alternatives.
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 already run Cloudflare's edge stack and have the engineering time for fallback origins and DCV: SSL for SaaS.
You want a bundled WAF per customer hostname and don't mind an unpriced bandwidth meter: SaaS Custom Domains.
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.
FAQ
What is the best custom domain API for a SaaS? For most teams before scale, Domainee: 50 domains and 100 GB free, then $0.20 per domain, with webhooks and an MCP server on every tier. For a large fleet already running Cloudflare's edge, SSL for SaaS wins on the raw $0.10-per-hostname rate. The cost table above prices both at 25, 100, and 500 domains.
Which custom domain API has a real free tier? Only Domainee has a permanent free tier (50 domains, 100 GB, no card). Cloudflare includes 100 hostnames but you manage the whole setup yourself. Approximated and CoAlias offer time- or request-limited trials, and Entri has no free tier at all.
How much does a custom domain API cost? Between $0 and about $0.20 per domain per month for the self-serve APIs, plus bandwidth where it's metered. The outlier is Entri at $749/mo once you add the SSL infrastructure. At 500 domains the self-serve options run roughly $40 (Cloudflare) to $100 (the $20-floor products), with Domainee at $90.
Which custom domain APIs support AI agents (MCP)? Domainee and Entri publish MCP servers. Domainee's is free-tier accessible and covers domain, DNS, and webhook operations; Entri's pairs with its $249+/mo plans. Approximated, CoAlias, and Cloudflare SSL for SaaS are REST-only, so you'd build the agent layer yourself.
Do I need Cloudflare to offer custom domains? No. Cloudflare SSL for SaaS is one option and it's strong at scale, but any of these APIs terminates TLS for your customers' hostnames and routes to your origin over a standard CNAME. Domainee, Approximated, and CoAlias all work regardless of what CDN or host serves your app.
Try Domainee free. 50 domains, 100 GB bandwidth, no credit card, no expiry. Every number on this page is published at /pricing.