Voice AI infrastructure · API-first

Voice AI infrastructure
for your product

Answers inbound callsBooks real appointmentsTexts mid-callTransfers to humansOutbound at scaleOne API · your numbers Answers inbound callsBooks real appointmentsTexts mid-callTransfers to humansOutbound at scaleOne API · your numbers
Real-time
Response
$0.08/min
All inclusive
15+
Languages
99.9%
Uptime SLA
BUILT FOR
Healthcare
Restaurants
Real Estate
Dental Clinics
Hotels
Marketing Agencies
Law Firms
E-commerce
SaaS Companies
Healthcare
Restaurants
Real Estate
Dental Clinics
Hotels
Marketing Agencies
Law Firms
E-commerce
SaaS Companies
HOW IT WORKS
Five steps. Real-time replies.
What happens between the question and the answer.
01
Caller speaks
Voice streams in
02
Transcribed
Voice to text
03
AI thinks
Reads + replies
04
Voice made
Text to speech
05
Caller hears
Natural reply
Real-time
Natural back-and-forth. Faster than a human.
Nixflex real-time
Human ~1.2s
WHO IT IS FOR
Two ways to go live
Build it yourself, or set it up without writing a line of code.
API-first

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
Read the docs

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
Read the setup guide
FOR DEVELOPERS
One API call.
Your number answers.
Create a voice agent on any phone number. That's it. Everything else is in the docs.
Read the docs
# Create an AI agent
curl -X POST https://api.nixflex.com/v1/agents
-H "Authorization: Bearer YOUR_KEY"
-d '{
"name": "Reception",
"system_prompt": "You are a friendly...",
"voice_id": "Ashley",
"language": "multi"
}'
# Returns agent_id - save it.
# Connect your own Twilio number
curl -X POST https://api.nixflex.com/v1/phone-numbers
-H "Authorization: Bearer YOUR_KEY"
-d '{
"phone_number": "+447446466847",
"twilio_sid": "ACxxxx",
"twilio_token": "xxxx",
"agent_id": "agent_125207e..."
}'
# Your number now answers with AI.
$curl https://api.nixflex.com/v1/calls?limit=1copy
WHAT IT CAN DO

Everything a phone line needs

Built in. No add-ons, no extra fees.

Live Monitor
Listen to your AI's calls as they happen - from the dashboard or inside your own app.
Learn more →
Appointment Booking
Books, reschedules and cancels with Cal.com and Google Calendar - and never fakes a booking.
Learn more →
SMS Agent
Two-way AI texting that answers customers and books over SMS. No platform fee.
Learn more →
Web Agent
The same AI on your website - one embed line, chats and converts visitors.
Learn more →
Outbound & Batch
Campaigns from a CSV - the AI calls, detects voicemail, and reports every result.
Learn more →
Call Transfer
Cold or warm hand-off to a human, with whisper - and back to AI if nobody answers.
Learn more →
Custom Functions·Post-Call Analysis·Webhooks·Bring Your Own Carrier
INTEGRATIONS
Every call sends data everywhere
After every call, the full record is sent to your systems — ready to flow anywhere.
Full transcript
Every word, both sides
Recording
MP3 link
AI summary
What was discussed
Sentiment
Happy, neutral, upset
Extracted data
Name, intent, more
FLOWS INTO YOUR TOOLS VIA ZAPIER & MAKE
Zapier
Make
HubSpot
Salesforce
GoHighLevel
Slack
Google Sheets
Airtable
Notion
Connects to your tools via webhooks, Zapier, and Make
No code needed · Data flows after every call
PRICING
Half the price. Everything included.
Others advertise low, then bill you for the LLM, the voice, the telephony, and add-ons. We don’t.
INDUSTRY AVERAGE
~$0.16
per minute, real cost
+ platform fees, add-ons,
up to 5 separate invoices
NIXFLEX
$0.08
per minute, flat · billed per second
Half the price · one bill
Speech recognition
Real-time, 15+ languages
AI reasoning
Real-time response
Natural voice
Human-quality speech
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
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.
See full pricing
$10 free credit to start · pay per second · no monthly fee · no setup fee
FAQ

Questions & answers

What is Nixflex?
+
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.
How does the AI sound so human?
+
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.
How long does setup take?
+
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.
Can I try it before I pay?
+
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.
How is Nixflex different from competitors?
+
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.
How is billing calculated?
+
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.
Are there any hidden fees?
+
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.
Is my data GDPR compliant?
+
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.
Can I delete my data?
+
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.
Still have a question?
Contact us →