Appointment booking
Books, reschedules and cancels with Cal.com and Google Calendar — and never fakes a booking.
Learn more
about Appointment booking
Loading your voice agent…
Get a Voice-AI
infrastructure
for your product.
Can I move my appointment to Wednesday 2:00 PM
Done, appointment updated
Nixflex is an AI voice platform for building real-time AI phone agents.
Nixflex is an AI voice platform for building real-time AI phone agents. Built for developers embedding voice agents into SaaS apps — and for businesses that want a phone agent without the plumbing.
Built for 50+ industries
- Response
- Real-time
- Languages
- 15+
- All inclusive
- $0.08 / min
- Uptime SLA
- 99.9%
Five steps.
Real-time replies.
- Step 1
Caller speaks
Receive the voice input from the caller
- Step 2
Transcribed
Translate the caller’s voice to text
- Step 3
AI thinks
AI reads the text and generates a reply
- Step 4
Voice made
Translate the reply from text to voice
- Step 5
Caller hears
Send the converted voice to the caller
Natural back-and-forth.
Faster than a human.
Nixflex real-timeHuman ~1.2s
Two ways to go live
Build it yourself, or set it up without writing a line of code.
For developers
Embed voice AI into your own app with one API call. Full control, your stack.
- REST API — bring your own Twilio or Telnyx
- 15+ languages, automatic switching
- Webhooks, transfers, bookings, custom functions
# Create an AI agent
curl -X POST https://api.nixflex.com/v1/agents \
-H "Authorization: Bearer YOUR_KEY" \
-H "Content-Type: application/json" \
-d '{
"name": "Reception",
"system_prompt": "You are a friendly receptionist.",
"voice_id": "Ashley",
"language": "multi"
}'
# Returns agent_id — save it.
For businesses
Set up your AI receptionist without code. Pick a voice, write what it says, connect a number.
- Guided setup in the dashboard
- Answers 24/7 in 15+ languages
- $0.08/min — everything included
One API call.
Your number
answers.
Create a voice agent on any phone number. That’s it.
Everything else is in the docs.
# Create an AI agent
curl -X POST https://api.nixflex.com/v1/agents \
-H "Authorization: Bearer YOUR_KEY" \
-H "Content-Type: application/json" \
-d '{
"name": "Reception",
"system_prompt": "You are a friendly receptionist.",
"voice_id": "Ashley",
"language": "multi"
}'
# Returns agent_id — save it.$ curl https://api.nixflex.com/v1/calls?limit=1Everything a
phone line needs
Built in. No add-ons, no extra fees.
about Appointment booking
Do you have anything tomorrow at 2?
Checking the calendar…
Confirmation sentSMS agent
Two-way AI texting that answers customers and books over SMS. No platform fee.
Learn more about SMS agentLive monitor
Listen to your AI’s calls as they happen — from the dashboard or inside your own app.
Learn more about Live monitorWeb agent
The same AI on your website — one embed line, chats and converts visitors.
Learn more about Web agentOutbound & Batch
Campaigns from a CSV — the AI calls, detects voicemail, and reports every result.
Learn more about Outbound & BatchCall transfer
Cold or warm hand-off to a human, with whisper — and back to AI if nobody answers.
Learn more about Call transferEvery call sends data
everywhere
After every call, the full record is sent to your
systems — ready to flow anywhere.
Extracted data
Name, intent, more
Full transcript
Every word, both sides
Sentiment
Happy, neutral, upset
Recording
MP3 link
AI summary
What was discussed
Flows into your tools via Zapier & Make
Half the price.
Everything included.
Others advertise low, then bill you for the LLM, the voice, the telephony, and add-ons. We don’t.
What’s included:
- Speech recognition
- Real-time, 15+ languages
- AI reasoning
- Real-time response
- Call recording
- Stored — yours via webhook link
- Post-call analysis
- Summary, sentiment, data
- Webhooks
- Delivery with auto-retries
- Unlimited agents
- No per-agent fees
- Dashboard + logs
- Included
- SMS agent
- No per-SMS platform fee
- Natural voice
- Human-quality speech
- Web agent
- Chat $0.01/msg · web calls $0.09/min
You bring your own carrier, so phone numbers, carrier minutes, and SMS are billed by Twilio or Telnyx
directly at their rates — Nixflex never marks them up.
Frequently
asked
questions
Nixflex is a developer-first voice AI platform for business phone calls. It combines speech-to-text, a language model, and natural text-to-speech into one real-time engine - so your AI answers, holds a natural conversation, books appointments, transfers to a human, and sends you the full transcript, recording, and data after every call.
Bring your own number from Twilio or Telnyx, control the AI with a simple prompt, and go live in minutes. Flat $0.08/min with no stacked fees, 15+ languages including Arabic.
We use the latest neural text-to-speech technology with natural voices across 15+ languages and accents. The AI responds in real time - faster than most humans - so conversations feel natural and fluid, not robotic.
Under 5 minutes. Create an account, set up your AI agent with a system prompt, connect your phone number from Twilio or Telnyx, and calls are answered immediately. Developers can do it in 5 lines of code.
Yes. Every new account gets $10 free credit - roughly 125 minutes of calls. No credit card required to sign up. You can test with real calls and only add a payment method when you're ready.
Four things. Price: at $0.08/min all-inclusive, we are roughly half the real cost of other platforms once their LLM and add-on fees stack up. Speed: real-time responses. Simplicity: you control the AI with a plain prompt - no complex flow-builders - and go live in minutes. And control: bring your own carrier number - Twilio or Telnyx (no lock-in), trigger your own APIs live during the call (not just after it), and white-label the whole thing under your own brand. Most platforms only send data after the call ends - Nixflex can act on it mid-conversation.
Billed per second at $0.08/min. No rounding up to the minute - a 45-second call costs about $0.06. No monthly fees, no hidden costs, no per-agent charges. Everything included.
No. $0.08/min covers everything. The only separate cost is your phone number and carrier minutes, paid directly to your own Twilio or Telnyx account at their local rates - Nixflex never marks them up.
Nixflex is built for GDPR: all call data is stored on EU infrastructure (Ireland), encrypted at rest (AES-256) and in transit (TLS 1.3), and auto-deletes 90 days after each call. See our Trust & Security page for the full picture of how data is processed.
Yes. Call data and recordings auto-delete 90 days after each call, and you can delete agents and phone numbers from the API or dashboard anytime. For removal of specific calls or full account deletion, email support@nixflex.com and we handle it within 30 days.
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