Synthflow vs Vapi for a phone receptionist
Synthflow and Vapi sit at opposite ends of how voice AI is bought. Synthflow's pricing page shows a single Enterprise card: contracts start at $30,000 a year, scoped around call volume, concurrency, telephony, integrations, security needs and launch support. Vapi is self-serve: $0.05 a minute in hosting, providers billed at cost, and $5 of free credit to start.
So the question is less about the rate and more about who does the work. Synthflow's pitch is fully tested agents delivered with launch support, under a contract. Vapi hands you the platform and a calculator, and your team builds and tunes the agent.
Synthflow suits an organization with high call volume, a budget for an annual contract and a wish to have the agent tested for it. Vapi suits a developer or product team that wants to start today and pay by the minute. Both pages were read on 24 September 2026.
Published pricing, side by side
What each vendor prints on its own site. The billing unit decides more of the final bill than the headline price does.
| Synthflow | Vapi | |
|---|---|---|
| Billing unit | Annual enterprise contract | Per minute, plus provider costs |
| Entry plan | Enterprise contracts from $30,000 a year | $0.05 a minute hosting, with transcription, model and voice passed through at cost; $5 in free credit to start |
| Higher tiers | Not published; scoped around call volume, concurrency, telephony, integrations and launch support | Core $29/mo (10 calls at once, 5 Vapi numbers); Pro at 10% of hosting with a $999/mo minimum (30 calls at once, 10 numbers); Premier custom |
| Overage rate | Not published; set inside each contract | Every minute is metered; Vapi's own calculator puts 1,000 minutes at $82–$129 a month |
Read on each vendor's own website in September 2026. Prices move, so check before you buy.
What decides it
The dimensions that change the bill or the service, each as a fact read on the vendor's own site.
| Synthflow | Vapi | |
|---|---|---|
| How you buy | Annual enterprise contract | Self-serve, pay as you go |
| Starting price | $30,000 a year | $0 to start, $0.05 a minute hosting |
| What sets the price | Call volume, concurrency, telephony, integrations, security, launch support | Minutes, the providers you pick, and your package |
| Support | Launch support scoped into the contract | Packages: Core $29 a month, Pro $999 minimum, Premier custom |
| Who builds the agent | Synthflow's pitch: fully tested agents | Your team, on Vapi's platform |
Synthflow: synthflow.ai/pricing. Vapi: vapi.ai/pricing and its calculator. Both read September 2026.
What Synthflow's single price card tells you
Synthflow's pricing page carries one card. It says enterprise contracts start at $30,000 annually, and that the final price is scoped by call volume, concurrency, telephony setup, integrations, security needs and launch support.
There are no self-serve plan prices on that page. You'll get a figure after a scoping conversation, so arrive knowing your monthly call count, how many calls arrive at once at your busiest hour, and which systems the agent must write to.
The contract model fits a call center or a multi-site operator that wants one accountable vendor. For a single office, the $30,000 floor is the first number to weigh.
What Vapi's self-serve start gives you
Vapi lets you begin with no package: $0 up front, $5 of free credit, one Vapi number and four calls at once. Hosting is $0.05 a minute, and transcription, the model and the voice are billed at each provider's price.
Vapi's calculator estimates 1,000 minutes at $82 to $129 a month. When you need more lines or longer data retention, Core is $29 a month for ten calls at once, and Pro carries a $999 monthly minimum for 30.
You can build and test on the free credit. Turning a test agent into a receptionist that books, transfers and knows your hours is the part your team builds.
Questions to settle before either one
How many calls reach you at once on your busiest morning? Synthflow prices concurrency into the contract, and Vapi raises it by package, so the number shapes both quotes.
Who will own the agent after launch? With Synthflow, ask what the contract covers once launch support ends. With Vapi, name the person who will update prompts when your prices or hours change.
For a business that wants the receptionist ready
Disclosure: GreetKeeper is our product, and this is its only mention on the page. It sits apart from both models: a finished AI receptionist with public monthly plans and no contract to scope. Starter is $49 for 200 answered calls, Professional $149 for 750 and Scale $349 for 2,000, with overage of $0.45, $0.35 or $0.25 a call.
Groups can take the Multi-location plan from $299 per location, and every location gets its own dedicated local number with its own hours, greeting and calendar. Calls that arrive together are answered at the same time.
GreetKeeper drafts its setup from your website for you to correct, books into Google Calendar or Outlook, and sends a signed webhook for every call to the system you choose. There's no setup fee, and every plan starts with a 14-day free trial, every feature on and no card.
| Plan | Monthly | Calls included | After that |
|---|---|---|---|
| StarterFor a single location taking calls one line at a time. | $49 | 200 | $0.45 per call |
| ProfessionalBooking, routing and transfers included, not an add-on. | $149 | 750 | $0.35 per call |
| ScaleFor busy phones and longer opening hours. | $349 | 2,000 | $0.25 per call |
Questions people ask about this comparison
How much does Synthflow cost?
Synthflow's pricing page says enterprise contracts start at $30,000 a year. The final price is scoped by call volume, concurrency, telephony, integrations, security and launch support, read September 2026. No self-serve plan prices appear on the page.
Is Vapi cheaper than Synthflow?
To start, yes. Vapi costs $0 up front with $5 of credit, then $0.05 a minute hosting plus provider costs. Its calculator puts 1,000 minutes at $82 to $129 a month. Synthflow's contracts start at $30,000 a year (September 2026).
Does Synthflow have a free plan?
Synthflow's pricing page shows only the Enterprise card, starting at $30,000 a year, read September 2026. Vapi's no-package start includes $5 of free credit, one number and four calls at once.
Which is better for a small business phone line, Synthflow or Vapi?
Vapi is the one a small business can start on without a contract, at $0.05 a minute plus providers. Synthflow's contracts start at $30,000 a year, scoped around volume and concurrency. Either way, someone has to build and maintain the receptionist logic.
Answer calls this week, no contract
Start GreetKeeper's 14-day trial with no card, then pick a monthly plan.