# Vapi, Retell and Synthflow alternatives for agencies (2026) By the Outbox AI team. Updated 2026-10-03. **If you're an agency reselling AI voice agents, the best alternatives to Vapi, Retell AI and Synthflow are whitelabel platforms that include client dashboards and rebilling out of the box: Outbox AI, Trillet, Autocalls and Stammer AI.** If you want to keep your existing Vapi or Retell agents, add a whitelabel layer like VoiceAIWrapper instead. > **Disclosure:** we make Outbox AI. Every competitor fact below comes from that company's own pricing page or docs, checked on 3 October 2026. ## Why agencies look for alternatives Vapi, Retell AI and Synthflow are all good at running voice agents. The problem for an agency is everything around the agent. - **Vapi and Retell are developer platforms.** Neither ships a whitelabel client portal or client rebilling. Both list third-party partners that add them (Vapify, VoiceAIWrapper, ChatDash and others). To sell to clients under your brand you add another vendor or build your own dashboard, billing and sub-accounts. - **Their per-minute price isn't the whole price.** - **Vapi:** $0.05/min for hosting. Transcription, model, voice and telephony are billed on top. - **Retell:** $0.055/min for voice infrastructure, plus model, voice and $0.015/min telephony. Retell estimates $0.07-$0.31 a minute all-in. - That's fine for one in-house build, but hard to quote to fifty clients. - **Synthflow changed course.** Synthflow's public pricing is now enterprise-only, starting at $30,000 a year. Its docs say the Stripe integration for reselling to sub-accounts was removed on 15 September 2026, so agencies that relied on it now bill clients themselves. ## Two ways to replace them ### Route 1: switch to an all-in-one whitelabel platform The platform runs the calls *and* gives you the branded client dashboard, sub-accounts and billing. One vendor, one bill, and a single per-minute price you can mark up. | Platform | Monthly from | Custom-domain whitelabel | Client rebilling | AI voice per minute | |---|---|---|---|---| | **Outbox AI** | $97 | From $97 (Starter) | Stripe, from $149 (Growth) | 14¢ / 12¢ / 10¢, model and voice included | | **Trillet** | $99 (1,000 min incl.) | $299 (Agency) | Stripe | $0.12 after included minutes, telephony extra | | **Stammer AI** | $49 ($99 for whitelabel) | $99 | Yes | $0.11-$0.17 by model | | **Autocalls** | $34 ($419 for whitelabel) | $419 monthly / $355 annual | Stripe | $0.09 overage on top tiers | | **Bland AI** | $0 (Start) | Not offered publicly | No | $0.14 (Start), $0.12 on the $299 Build plan | ### Route 2: keep Vapi or Retell and add a whitelabel layer If you've already invested in Vapi or Retell agents, a wrapper gives you the client-facing layer without migrating. **VoiceAIWrapper** ($79-$499/month) sits on top of Vapi, Retell, ElevenLabs, Bolna or Ultravox using your own keys. It adds a custom domain, client accounts and Stripe rebilling, with no per-minute markup. The trade-off: you still pay your provider's separate model, voice and phone charges, you manage two vendors, and CRM integrations like GoHighLevel run through webhooks. ## Outbox AI as a Vapi, Retell or Synthflow alternative [Outbox AI](/guides/what-is-outbox-ai) is built for the agency use case these tools leave to you. - **Whitelabel from day one:** your logo, custom domain and sender email on the $97 Starter plan. - **Rebilling built in:** connect your Stripe account, set your own per-minute and per-message rates, and client wallets top up automatically (Growth and up). There's no revenue share, and you can publish self-serve SaaS plans for clients. - **One predictable rate:** 14¢, 12¢ or 10¢ a minute depending on plan, with model usage included, so you can quote clients a margin without a spreadsheet. - **Production voice:** sub-800ms responses, barge-in, and warm transfers with a summary or a concierge-style handover. Runs on Twilio, Vonage, Telnyx or SIP. - **More than voice:** chat agents on SMS, WhatsApp, Messenger, Instagram and web, plus workflows and AI-built client websites, under the same brand. - **Native GoHighLevel:** a marketplace app with *Send AI Call* and AI chat workflow actions ([details](/guides/gohighlevel-ai-voice-agent)). **Where Vapi or Retell is still the better pick:** if you're a developer building one highly custom agent and want low-level control over every model, voice and telephony component, the raw APIs give you more knobs. Outbox trades some of that low-level control for a platform you can sell from on day one. ## Migrating from Synthflow, Vapi or Retell 1. **Export your prompts.** Your system prompt, first message and knowledge base text carry over almost as-is. 2. **List your tools.** Map each function or webhook to the new platform's equivalent. On Outbox that's a built-in tool (book appointment, SMS, transfer, CRM update), a custom webhook, or an MCP server. 3. **Move or forward your numbers.** Bring your Twilio, Telnyx or Vonage numbers, or point your SIP trunk at the new platform. 4. **Run both side by side** on a test number for a few days, using the same scripts, and compare responses, booking accuracy and cost per call. 5. **Switch the client over,** then turn on rebilling. ## Frequently asked questions ### What is the best Vapi alternative for agencies? For agencies that resell to clients, an all-in-one whitelabel platform such as Outbox AI, Trillet or Autocalls is usually better than Vapi, because it includes branded client dashboards, sub-accounts and rebilling. Vapi is a developer API without those agency features. ### What is the best Synthflow alternative after the 2026 pricing change? Agencies that relied on Synthflow's sub-account reselling, which was removed on 15 September 2026, should look at platforms with built-in Stripe rebilling. Outbox AI (from $149/month), Trillet (from $99/month) and Autocalls (from $355/month annual) all include it. ### Is Retell AI white-label? Not natively. Retell has no whitelabel client portal or client rebilling of its own, but lists third-party partners that add them. Alternatively, use a platform like Outbox AI that includes whitelabel and rebilling. ### How much does Vapi really cost per minute? Vapi charges $0.05 a minute for hosting, plus transcription, the language model, the voice and telephony, each billed at the provider's rate. Retell estimates $0.07-$0.31 a minute all-in for its own platform. Outbox AI charges 10-14¢ a minute with model and voice included; carrier minutes are billed by your carrier. ### Can I keep my Vapi agents and still whitelabel them? Yes. Tools like VoiceAIWrapper add a whitelabel client portal and Stripe rebilling on top of your existing Vapi or Retell account. ## Sources Checked on official sites on 3 October 2026: [Vapi pricing](https://vapi.ai/pricing), [Vapi whitelabel partners](https://docs.vapi.ai/providers/voiceaiwrapper), [Retell AI pricing](https://www.retellai.com/pricing), [Retell app partners](https://www.retellai.com/app-partner), [Synthflow pricing](https://synthflow.ai/pricing), [Synthflow Stripe reselling notice](https://docs.synthflow.ai/stripe-overview), [Trillet whitelabel pricing](https://trillet.ai/whitelabel/pricing), [Stammer AI pricing](https://stammer.ai/pricing), [Autocalls pricing](https://autocalls.ai/pricing), [Bland AI pricing](https://www.bland.ai/pricing), [VoiceAIWrapper pricing](https://voiceaiwrapper.com/pricing).