Fonio.ai: How Daniel Keinrath won 1,700 Customers in 10 Months with His Phone AI
Volume #26 of "Happy Bootstrapping" Newsletter
Daniel Keinrath and his co-founder Matthias built Fonio.ai, an AI phone assistant that already serves over 1,700 customers. In just 10 months, they reached $2 million ARR – completely bootstrapped. At 15 cents per minute with the fastest latency in the German-speaking market, they're attacking established providers.
This is a summary of Episode 137 of the “Happy Bootstrapping” Podcast (German).
The Founding Story: From San Francisco to Vienna
Daniel was actually on his way to the USA. After selling his influencer startup Getnano in early 2023, he wanted to found in San Francisco. But his encounter with Voice AI changed everything: "I noticed that it was still quite clunky even in English." The pragmatic realization: Europe offers an advantage.
Back in Vienna, he convinced Matthias – after three rejections. The proof of concept was radical:
"I had already sold Fonio before the product existed."
With 1,000 euros in ads and a landing page, Daniel called through all leads and sold the non-existent product ten times. The first real customer went live at the end of September 2023.
The Business Model: Self-Service Meets Enterprise
Fonio works remarkably simply:
300 euro minimum credit to start
Self-service onboarding in minutes
15 cents per minute (recently reduced from 25 cents)
Up to 20 parallel calls possible
"You go to our website, click start now," Daniel explains the process. The AI is trained with prompts, can use PDFs as context, and access live data via APIs during calls. The average setup takes four hours – for simple use cases, it goes live in one to two weeks.
Surprisingly: 500 new customers in July 2024 alone. The strategic price reduction is deliberate: "My approach is, I believe that software itself is becoming a commodity."
Marketing and Biggest Challenges
The marketing mix surprises:
85,000 euros monthly ad spend
Instagram and Facebook work better than LinkedIn
Over 400 reviews across various platforms
500-600 daily test calls via the website
"My take on it is that it's no longer about leisure time or not. We're all on our phones," Daniel explains the B2B success on Instagram.
The biggest operational challenge is paradoxical: growing too fast. The 300 euro entry barrier is intentional – without it, they'd get 2,000-3,000 new customers monthly. "But that would mean we couldn't provide support anymore."
The Tech Stack: Speed as a Weapon
Fonio uses an "orchestration layer" with a clear strategy:
OpenAI GPT-4.o mini on Azure servers in Sweden
Voices from third-party providers (Cartesia, ElevenLabs)
Hosting at Hetzner in Nuremberg
"We have no one worldwide who beats us on German latency"
The division of work between the founders is radical: "We make decisions like one person, not two people." Daniel is responsible for commercial, Matthias for product. They've only met physically three times since founding.
Daniel's Learnings from 10 Months of Hypergrowth:
The 300 euro hurdle was the most important decision
Stay small and force everyone to use AI
Ownership instead of micromanagement
Lowering prices instead of raising protects from competition
At 35% monthly growth, you don't need VC money
"It feels a bit like playing computer games right now. Constantly leveling up," Daniel describes the current phase. With planned expansions to France, Poland, and Italy, the next level is already waiting.
What I Learned as an Interviewer
I was particularly impressed by Daniel's radical approach to proof of concept – selling a non-existent product requires courage. The price reduction during explosive growth contradicts every textbook opinion but makes strategic sense. I was surprised that B2B marketing works better on Instagram than LinkedIn. And the working relationship with Matthias – three meetings in a year at this growth speed – shows how efficient modern founding teams can be.
Happy Bootstrapping is a German podcast where I interview bootstrapped founders, indie hackers, and solopreneurs about their startup journeys.
Over the years, I've connected with many successful entrepreneurs who have built e-commerce shops, SaaS platforms, mobile apps, content businesses, or hybrid models.
Furthermore I am a bootstrapper myself and growing my DevOps-as-a-Sercice and Web Operations Company “We Manage”.