I ship in production
what others take quarters to release.
Sacha Praljak. Founder & senior engineer. I build and operate Kryva and Krydor. Freelance: Claude tool-use, voice agents, Stripe Connect, Next.js 16. Remote worldwide.
Work
Two ventures. One operator.
My own products, built solo and run in production. They're the proving ground for everything I sell as freelance work.
Kryva
Founder & Lead Engineer · 2025 — present
B2B SaaS for French construction trades — in production for 6+ months, weekly iterations.
Voice-driven AI quotes (inbound ARC agent), Stripe payments, e-signature, KYB, FEC-compliant accounting + Factur-X e-invoicing PDP. Claude tool-use agent with 40+ tools, Stripe Connect Express marketplace with automated commissions, enriched Apollo lead pipeline. GDPR + EU AI Act compliant. Paid Vapi diagnostic mission in progress in parallel.
Krydor
Founder · 2026 — under construction
Network of RGE-certified construction trades with MaPrimeRénov' simulator and AI quotes in under 5 minutes.
Kryva's B2C distribution channel: French government renovation grant simulator, instant eligibility check, AI-priced pre-quote via ARC (Kryva), project pooling between network artisans. Disrupting a lead-gen market (Effy, Hellio) stuck on "call within 48h, quote within 2 weeks".
What I do
Three areas. Production-ready by default.
Everything below already runs in prod on Kryva. No demos, no side-projects — code tested in real conditions for 6+ months.
Production AI engineering
No POCs. Agents and systems that actually run in production — with audit trails, error recovery, and a proper human layer on top.
- —Claude tool-use agents (40+ tools live on Kryva)
- —Human-in-the-loop gates, streaming, cross-tool state
- —Vapi voice agents (STT/endpointing/tuning), EU AI Act art.50 compliant, paid diagnostic mission in progress
- —Multi-agent architecture, observability, replay
Backend & marketplace
The engine behind the product: monetization, compliance, scale. Built to last beyond v1.
- —Stripe Connect Express: KYC, commissions, monthly auto-payouts
- —Multi-modal auth: passkeys, OAuth, magic links, e-signature
- —Supabase RLS multi-tenant, Edge Functions, Vercel cron
- —GDPR + EU AI Act compliance, multi-country retention
Frontend & growth
Modern Next.js, solid SEO, conversion that holds. Shipped, not shipped-ish.
- —Next.js 16 RSC + Server Actions, advanced App Router
- —Technical SEO (Core Web Vitals, structured data, AI-citability)
- —Apollo pipeline: enriched B2B leads, multi-channel email + SMS sequences
- —Tailwind design system, motion/react animations
Packages
Fixed prices. Clear deliverables.
50% on signature, 50% on delivery. All packages delivered remotely, in English or French.
1-day Discovery
AI audit + 90-day roadmap
Claude tool-use MVP
★ Most pickedVapi voice agent diagnostic
Vapi voice agent in prod
Stripe Connect marketplace
Next.js feature sprint
Custom day rate
Process
From brief to delivery in five steps.
Send me a brief
Calendly 15 min or the form at the bottom of this page. Three lines is enough: business goal, current stack, deadline.
Qualification in 15 minutes
I tell you whether it's a fit, under what format (fixed-price or day-rate), and what's a realistic deadline.
Proposal within 24 hours
1-2 page quote with precise deliverables, schedule, fixed price. Valid for 7 days.
Deposit & kickoff
50% on signature triggers the kickoff. Async daily updates, weekly demo if the engagement is over a week.
Delivery & handover
Code on your repo, README up to date, 30-min handover call. Free bug fixes for 14 days after delivery.
About
Sacha Praljak.
Founder of Kryva and Krydor. 8+ years in tech, 5 of those on B2B products in production (SaaS, fintech, marketplaces).
I built Kryva solo, in production for 6+ months: a complete B2B SaaS with voice-driven AI quotes (inbound ARC agent), Stripe payments, KYB, e-signature, FEC accounting + Factur-X e-invoicing PDP. Plus a Claude tool-use agent with 40+ tools, a Stripe Connect marketplace with automated payouts, and an enriched Apollo B2B lead pipeline.
In parallel I'm building Krydor — Kryva's B2C distribution channel, disrupting a €4B/year market by delivering a priced quote in under 5 minutes where incumbents take 2 weeks.
On the freelance side: a paid Vapi diagnostic mission in progress (STT nova-3 + endpointing + AI Act art.50) — French voice AI over the phone has been my daily terrain for a year.
EN / FR fluent. Daily stack: Next.js 16, Supabase RLS, Claude API, Vapi, Stripe Connect, Apollo, Resend. Remote — EU + US East Coast overlap.
FAQ
Frequently asked.
When can you start?+
This week. Full-time availability — I can dedicate myself entirely to your project.
Day rate or fixed-price?+
Preference for fixed-price when scope is clear (deliverables, schedule, fixed prices). Day rate $1,100 for engagements where scope evolves.
Long engagements (3+ months)?+
Yes. Whether one week or six months, I commit full-time as long as the engagement is well-defined and the scope is clear.
NDA / confidentiality?+
Yes, I sign standard NDAs. For sensitive projects I offer a mutual NDA of my own.
Payment terms?+
Bank transfer or Stripe (link provided on signature). 50% on signature, 50% on delivery. For packages >$5k, three milestones are possible.
Tax setup?+
French auto-entrepreneur (sole proprietor), SIRET provided, compliant invoices. VAT not applicable (art. 293 B French tax code).
Outside France?+
No issue — I work remotely with clients in the EU, UK, US, Switzerland. Contracts in English, payment in EUR or USD via Stripe or Wise. CET timezone (Paris), EU + US East Coast overlap.
Currency?+
EUR or USD, your choice. Equivalent rates: ≈ €1,000/day, ≈ €4,500 for the 5-day Claude MVP.
Available. Now.
Fifteen minutes is enough to qualify your need and tell you if I'm the right match.
Book 15 minutes