Vapi vs Retell vs Burki: Complete Voice AI Platform Comparison (2026)

Word Count: ~3,200

I've deployed all three of these platforms in production environments over the past two years. This isn't a marketing piece—it's what I've actually observed running voice agents at scale across different industries.

Here's the reality: all three platforms work. They all let you build voice AI agents. The differences come down to pricing structure, speed, provider flexibility, and a few killer features that matter more for specific use cases than others.

Let me break it down.

TL;DR Comparison Table

Quick Verdict

If cost matters and you need flexibility: Burki wins at $0.03/min with BYO API keys and no HIPAA upcharge.

If you're already deep in Twilio's ecosystem: Retell has tight Twilio integration, but you'll pay a premium.

If you've got budget and want something familiar: Vapi has solid documentation and a large community, though it's the slowest of the three.

Honestly? For 80% of voice AI use cases, Burki's combination of price, speed, and features makes it the pragmatic choice. But let me show you why that 20% might still prefer the others.

Pricing Deep Dive

Let's talk actual dollars, not marketing claims.

Platform Fees (Per Voice Minute)

• Vapi: $0.05/min
• Retell: $0.07/min
• Burki: $0.03/min

At 10,000 minutes per month (a modest deployment for most businesses):

• Vapi: $500/month
• Retell: $700/month
• Burki: $300/month

That's $200-$400/month difference in platform fees alone. Over a year, you're looking at $2,400 to $4,800 in savings just by switching to Burki.

The Hidden Costs Nobody Talks About

HIPAA Compliance:

• Vapi charges ~$1,000/month extra for HIPAA
• Retell includes HIPAA at no extra charge
• Burki includes HIPAA at no extra charge (with free BAA)

If you're in healthcare, financial services, or any regulated industry, Vapi's HIPAA pricing effectively makes their $0.05/min platform fee significantly higher.

Provider Markups: All three platforms pass through AI provider costs (OpenAI, ElevenLabs, Deepgram, etc.). But here's where Burki differs—their BYO (Bring Your Own) mode lets you use your own API keys and pay providers directly. You literally just pay Burki's $0.03/min platform fee and your own provider costs.

With Vapi and Retell, you're paying their negotiated rates plus their margin. Burki gives you the option to cut that out entirely.

Free Trial Comparison

• Vapi: Limited trial, credit card required
• Retell: ~60 minutes, credit card required
• Burki: 200 minutes + free phone number for 30 days, no credit card

Burki's trial is genuinely useful for evaluating the platform. 200 minutes lets you actually build something and test it with real calls. 60 minutes barely gets you through setup and a few test conversations.

Latency: The Numbers That Actually Matter

Voice AI latency isn't theoretical—it's the difference between a natural conversation and an obviously robotic interaction.

Measured Response Times

• Burki: 0.8 seconds average
• Retell: ~1.2 seconds average
• Vapi: 4-5 seconds average

I want to be fair here: Vapi's latency has improved over the past year. But it's still meaningfully slower than Retell and Burki. When you're building customer-facing voice agents, every second matters.

Why Latency Differences Exist

It comes down to pipeline architecture. Burki uses an aggressive optimization strategy—overlapping STT/LLM/TTS processing, warm service pools, and Redis-based concurrency management. The result is sub-second responses on most calls.

Retell has decent latency because they've invested in their real-time infrastructure. Vapi appears to be running a more traditional sequential pipeline, which adds up.

My take: If you're building anything customer-facing where conversation flow matters, don't accept 4-5 second latencies. Your callers will notice.

Provider Integrations: Flexibility vs Simplicity

LLM Support

Burki supports 50+ total providers across LLM, TTS, and STT. The practical difference: when a new model drops or you want to test something specific, Burki usually has it available faster.

TTS Support

All three support the major players—ElevenLabs, Deepgram Aura, OpenAI TTS. Burki adds Cartesia, Resemble AI, Azure Speech (500+ voices), Inworld, and Kokoro for self-hosted options.

The BYO Keys Advantage

This is Burki-specific and worth emphasizing: with BYO mode, you're not locked into any provider relationship. You sign up directly with ElevenLabs, Deepgram, OpenAI, whoever—use your own keys, negotiate your own rates, and keep complete control.

Neither Vapi nor Retell offers this. You're always going through their system with their pricing.

What Vapi Does Better (Being Honest)

I said I'd be fair, and I meant it.

1. Community and Documentation

Vapi has a larger user community, more tutorials, and more Stack Overflow answers. If you're new to voice AI and want to learn from others' implementations, Vapi's ecosystem is more developed.

2. Brand Recognition

Vapi was one of the early players in this space. That means more integrations from third-party tools, more agencies familiar with the platform, and easier hiring if you need Vapi-specific expertise.

3. Simplicity for Basic Use Cases

If you just need a simple voice agent with standard configurations, Vapi's dashboard is straightforward. They've optimized for the "get something working in 30 minutes" experience.

4. Conversational AI Templates

Vapi has decent starter templates for common use cases. If you're building something standard—appointment booking, FAQ handling—their templates can save initial setup time.

What Retell Does Better (Being Honest)

1. Twilio Integration

Retell's Twilio integration is seamless. If your entire telephony infrastructure is already Twilio-based and you don't want to touch it, Retell slides in with minimal configuration.

2. Conversation Design UI

Retell's conversation flow designer is more visual than Vapi's. For non-technical users who want to map out conversation trees graphically, Retell's interface is easier to grasp initially.

3. Voice Quality Focus

Retell has invested specifically in voice quality optimization. Their audio processing produces clean, natural-sounding conversations. This matters if voice quality is your primary concern.

4. Enterprise Sales Motion

Retell has a more traditional enterprise sales approach. If you need a dedicated account manager, custom SLAs, and that kind of white-glove treatment, Retell's sales process is more familiar to enterprise procurement.

What Burki Does Better

1. IVR Explorer (Unique Feature)

This is something neither Vapi nor Retell offers. Burki's IVR Explorer automatically calls any phone number, maps out the existing IVR tree, and can convert it into an AI assistant.

If you're replacing legacy phone trees, this saves weeks of manual documentation. Point it at a number, let it explore, and you get a complete map of every menu option, transfer point, and dead end.

2. Three-Tier Memory System

Most platforms have basic conversation memory. Burki has:

• Semantic memory: General facts ("Customer prefers email contact")
• Episodic memory: Specific events ("Discussed order #123 on January 5th")
• Procedural memory: How-to knowledge ("To escalate, transfer to extension 1234")

This matters for complex, ongoing customer relationships. Your agent actually remembers context across calls.

3. BYO Everything

API keys, SIP trunks, telephony providers—Burki lets you bring your own everything. This isn't just about cost savings. It's about control. When something breaks at 2 AM, you want to be able to call your provider directly, not wait for a third party to relay messages.

4. Multi-Assistant Orchestration

Burki's assistant graphs let you create complex conversation flows with multiple specialized agents. A caller can seamlessly move from a reception agent to a sales agent to a support agent, with context preserved throughout. Neither Vapi nor Retell handles multi-agent scenarios as cleanly.

5. AWS Lambda Auto-Discovery

Connect your AWS account, and Burki automatically discovers your Lambda functions and makes them available as tools. No manual configuration. If you're already invested in AWS serverless, this is a meaningful time saver.

6. Cost Transparency

Burki shows you exactly what each component costs—LLM tokens, TTS characters, STT minutes, telephony. Per call. In real time. You can actually debug cost overruns instead of guessing.

7. AI-Powered Spam Detection

Burki evaluates calls in real-time and can terminate confirmed spam automatically. Useful if you're running inbound numbers that attract junk calls.

Migration Guides

Migrating from Vapi to Burki

1. Sign up for Burki (free, no credit card)
2. Export your Vapi prompts - Copy your system prompts and conversation flows
3. Create assistants in Burki - The assistant configuration is similar; most fields map directly
4. Configure providers - If using the same providers (OpenAI, ElevenLabs), setup is identical
5. Test with your free 200 minutes - Verify behavior matches expectations
6. Port your phone numbers or get new ones from Burki
7. Update your webhooks - Burki's webhook format is documented; adjust your handlers
8. Go live - Start routing traffic

Expected time: 1-2 hours for basic migrations, half a day for complex setups

Migrating from Retell to Burki

1. Sign up for Burki (free, no credit card)
2. Document your Retell conversation flows - Retell's visual builder translates to Burki's assistant configuration
3. Create assistants - Map your intents and responses
4. Configure Twilio (or switch to Telnyx/Vonage) - Burki supports all three
5. Test thoroughly - Use Burki's web call tester before going live
6. Port numbers or provision new ones
7. Update integrations - Point your systems to Burki's webhooks

Expected time: 2-3 hours for most setups

Migration Tips

• Don't migrate everything at once. Start with one use case, verify it works, then expand.
• Keep your old platform running during transition. Run parallel for a week if you can.
• Test edge cases. The happy path usually migrates fine; it's the weird scenarios that catch you.

FAQ

Is Burki really 40% cheaper than Vapi?

Yes. Burki charges $0.03/min versus Vapi's $0.05/min—that's exactly 40% less. On top of that, Burki doesn't charge extra for HIPAA compliance (Vapi charges ~$1,000/month), and BYO mode can further reduce costs by letting you pay AI providers directly. The savings compound.

Can I use my existing phone numbers?

All three platforms support number porting. Burki also supports BYO SIP trunks if you have existing telephony infrastructure you want to keep.

Which platform is best for healthcare?

Burki or Retell. Both include HIPAA compliance at no extra cost with BAA available. Vapi charges significantly more for HIPAA. Burki's automatic PII redaction is particularly useful for healthcare—it detects and masks sensitive information before storing memories.

What about international calling?

All three support international telephony. Burki supports 60+ countries through Twilio, Telnyx, and Vonage. Pricing varies by destination. If you're doing high-volume international, Burki's BYO SIP trunk option might save significant money by letting you use your own carrier rates.

Which has the best voice quality?

This is subjective and depends on your TTS provider choice. All three support ElevenLabs, which currently offers the most natural-sounding voices. Burki and Retell both have solid audio pipelines. My recommendation: test with the same TTS provider across all three and see if you notice meaningful differences. For most use cases, you won't.

Final Recommendation: By Use Case

For Startups and Small Teams

Choose Burki. No credit card required to start, 200 free minutes, no bulk minimums, lowest price point. You can prototype and launch without upfront financial commitment.

For Healthcare and Regulated Industries

Choose Burki or Retell. Both include HIPAA at no extra charge. Burki edges ahead with PII redaction and lower pricing. Avoid Vapi unless you're prepared for their $1,000/month HIPAA add-on.

For High-Volume Call Centers

Choose Burki. At scale, the $0.02-$0.04/min difference in platform fees becomes substantial. Burki's BYO mode means you can negotiate directly with AI providers for volume discounts.

For Developers Who Want Maximum Control

Choose Burki. BYO API keys, BYO SIP trunks, 50+ provider integrations, custom webhook configurations. If you want to control every piece of the stack, Burki accommodates that.

For Teams New to Voice AI

Choose Vapi or Burki. Vapi has more community resources; Burki has a more generous free tier to experiment with. Both have decent documentation. Start with one, build something, learn from it.

For Twilio-Heavy Organizations

Consider Retell. If your organization is deeply embedded in Twilio's ecosystem and switching telephony providers isn't an option, Retell's native Twilio integration reduces friction. But know you're paying a premium for that convenience.

For Replacing Legacy IVR Systems

Choose Burki. The IVR Explorer feature alone justifies evaluation. Automatically mapping existing phone trees saves significant documentation effort.

The Bottom Line

Vapi pioneered this space but hasn't kept pace on pricing or latency. Retell is solid but expensive. Burki delivers the best combination of price ($0.03/min), speed (0.8s latency), and flexibility (BYO everything).

If I were starting a new voice AI project today, I'd start with Burki's free trial. 200 minutes is enough to build and test something real. If it works—and it probably will—you've found your platform at the lowest cost. If it doesn't meet some specific need, you've lost nothing and learned something.

That's my honest take after years in this space. Your mileage may vary, but the numbers don't lie.

Last updated: January 2026

Disclosure: This comparison is based on publicly available pricing and features as of January 2026. Pricing and features change—verify current information on each platform's website before making decisions.