comparison · voice infrastructure
VAPI vs Assistable in 2026: Voice Infrastructure API Comparison
By builders, for builders.
VAPI and Assistable are both voice AI infrastructure API providers. They serve developers and builders who want to define voice agents programmatically and run them at scale. If you are deciding between VAPI and Assistable, you are likely asking the right question: VAPI is more mature and widely used; Assistable is a newer, cheaper alternative. However, this comparison matters less than you might think. The real inflection point for voice AI builders is not choosing between two similar infrastructure APIs, but deciding whether to build operations and agency logic on top of APIs, or to use a platform that does that for you.
VAPI: the more mature choice
VAPI has built a strong brand among voice AI developers. Its TypeScript and Python SDKs are well-maintained, its documentation is comprehensive, and its developer community is active. VAPI also has a track record of reliability: no major outages in 2025 or 2026. The tradeoff is cost: VAPI's platform fee is on the higher end of the infrastructure market. However, the peace of mind and time savings from good SDKs and responsive support often justify the cost. If you are building a mission-critical voice application and can afford the extra USD 100 to 300 per month, VAPI is the safer bet.
Assistable: the cost-optimized alternative
Assistable entered the market around 2024 with a positioning as a cheaper VAPI alternative. Assistable's core infrastructure is solid, and its pricing is genuinely lower: USD 0.08 to 0.14 per minute versus VAPI's 0.09 to 0.15 per minute. At scale (10,000 minutes per month), Assistable could save you USD 100 to 600 per month. The tradeoff is a smaller developer community, less mature documentation, and a shorter track record. If you are cost-optimizing and have the engineering horsepower to solve problems without handholding, Assistable is a valid option.
Side-by-side comparison
| Feature | VAPI | Assistable |
|---|---|---|
| What it is | Voice AI infrastructure API | Voice AI infrastructure API |
| Platform fee per minute | Approx USD 0.09 to 0.15/min | Approx USD 0.08 to 0.14/min |
| Total cost at 5,000 min/mo (with LLM/TTS) | Approx USD 650 to 1,500/mo | Approx USD 600 to 1,400/mo |
| p50 latency | 600ms to 900ms (standard) | 700ms to 950ms |
| p95 latency | 1.2 to 1.5 seconds | 1.3 to 1.8 seconds |
| SDK quality (TypeScript, Python) | Excellent, well-maintained | Good, smaller community |
| Documentation | Comprehensive, many examples | Adequate, fewer recipes |
| Developer support | Responsive, Discord community active | Basic, limited community |
| Uptime / reliability history | 99.9+ percent, mature ops | 98 to 99 percent, fewer battle scars |
| Multi-workspace / billing | No; raw infrastructure | No; raw infrastructure |
| CRM integration | Via webhooks + your code | Via webhooks + your code |
| White-label options | No; API only | No; API only |
| Best for | Developers building custom voice AI products | Cost-optimized API access with smaller dev teams |
The larger question: API vs platform
Whether you choose VAPI or Assistable, you are making a bet that you will build (or already have built) all the operations logic on top of the infrastructure. That means: CRM, contact management, billing, multi-workspace isolation, white-label client portals, outbound campaigns, per-client P&L tracking. If you are doing this alone, budget 6 to 12 months and USD 50K to 150K in development cost for the initial build. If you are an agency operator trying to serve 5 to 20 clients, VAPI + Assistable + DIY operations is a losing bet. You will spend more time on infrastructure maintenance than on client delivery.
This is why agencies that start on VAPI or Assistable eventually move to a platform. Hermes is built on top of infrastructure providers like VAPI and Retell, and it abstracts all the operations complexity. Most operators who have tried both report that Hermes reduces time-to-deployment by 60 to 80 percent and frees up engineering cycles to focus on client outcomes instead of platform plumbing.
FAQ
What is VAPI?
VAPI is a voice AI infrastructure API provider. It handles telephony, voice model integration, LLM routing, and conversation state management. Developers define agent configurations in JSON or code, and VAPI manages the call lifecycle. VAPI is known for strong SDK quality (TypeScript, Python), good latency characteristics (p50 typically 600ms to 900ms), and responsive developer support. Pricing is roughly USD 0.09 to 0.15 per minute for platform fees on top of underlying LLM and TTS model costs, putting total cost around USD 0.13 to 0.30 per minute depending on model selection. VAPI is popular with startups building voice AI products and with agencies building custom solutions.
What is Assistable?
Assistable is a smaller voice AI infrastructure provider that emerged around the same time as VAPI. It offers similar core capabilities: agent definition, call routing, multi-model support. Assistable's positioning is as a more cost-efficient alternative to VAPI, with pricing around USD 0.08 to 0.14 per minute for platform fees. Assistable is less widely adopted than VAPI, with a smaller developer community and fewer case studies in production. Latency and reliability have been adequate but not exceptional, and developer support is more limited than VAPI.
How does latency compare between VAPI and Assistable?
VAPI targets p50 latencies of 600ms to 900ms for most conversational flows, with p95 latencies around 1.2 to 1.5 seconds. Assistable reports similar targets, with p50 around 700ms to 950ms. In practice, both are acceptable for most voice agent use cases. The difference between VAPI and Assistable on latency is marginal for synchronous conversations. Where they differ is in reliability during peak hours: VAPI's infrastructure has been battle-tested at scale; Assistable's outage history is less mature.
Who should use VAPI versus Assistable, or should we consider Hermes?
Use VAPI if you are a developer building a custom voice AI product, need best-in-class SDK quality, or want the most mature API infrastructure. VAPI is the safer choice if reliability matters. Use Assistable if you are cost-optimizing and have tolerance for a smaller community and less mature support. If you are an agency operator (not a developer), neither VAPI nor Assistable is the right choice: they are infrastructure APIs, not agency platforms. You will need to build or buy a complete operations layer on top (CRM, white-label portal, billing, contact management, campaigns). Hermes solves that problem: it is built on top of infrastructure providers like VAPI and Retell and adds the entire agency operations layer. Most developers who start on VAPI and want to serve agencies eventually move to Hermes or hire a team to build what Hermes provides.
Building an agency? Skip the infrastructure DIY.
Hermes is the operating platform for AI voice agencies. Built on reliable infrastructure, with native CRM, billing, campaigns, and white-label ops. From $149/mo.
Apply to the Founders' Beta