Daniel Cramer · Full-stack developer, SaaS and AI

Software that proves what it promises.

I build web and desktop applications from the database to the interface and take them into production: multi-tenant B2B platforms, AI features with measurable quality, payments and integrations. Three of my own products are live.

Start a project See the work

Test run

Demonstration

Tenant A sees no data from tenant BRLSAccess rule removed · expected: 0 foreign rows · received: 14
Credentials are stored encryptedAES-GCM
Answer uses the customer's knowledge10 of 12 key facts
Undeterminable counts as nofail-closed

4 passed · 0 failed

A test that can never fail proves nothing. That's why I inject the fault myself first.

Built for

Measurement log

What can be proven

Claim	Measured	Method
Own products in production	3	live: einwandfr.ai, cloora.de, optimavo.de
Answer quality with customer knowledge	10 of 12 key facts	same customer question without that knowledge: 0 of 12. Fixed key facts, grading model
Automated tests (Cloora)	308	plus probes against the live database, permissions and tenant isolation per role
Review sources (Optimavo)	6 platforms	Google, Trustpilot, Tripadvisor, Trusted Shops, Yelp, ProvenExpert
Desktop platforms	macOS and Windows	signed, notarized, automatic updates

Work

Four inspection reports

einwandfr.ai

einwandfr.ai open

Einwandfr.ai

AI copilot for sales calls

What it does: Listens to the sales call live, detects objections and shows the rep the right answer within seconds. Every company stores its own sales knowledge.
What I built: Desktop app for macOS and Windows plus web dashboard
Real-time transcription and answers with Claude
Stripe subscriptions with team seats
CRM and calendar integrations via OAuth
Stack: TypeScript
React
Electron
Supabase
Anthropic Claude
AssemblyAI
Stripe

Evidence

The same customer question, once with and once without the stored knowledge.

10 of 12 key facts

cloora.de

cloora.de open

Cloora

CRM and sales management for setter-closer teams

What it does: Multi-tenant CRM with contacts, deals, call histories, appointments, analytics and roles. Built from a complete design, all 10 pages.
What I built: PostgreSQL with row-level security and tenant isolation
Roles and permissions per team
Encrypted mailbox connection: Gmail, Microsoft, SMTP
Analytics and sales management
Stack: TypeScript
React
PostgreSQL
Row-Level Security
AES-GCM

Evidence

308 automated tests, plus probes against the live database that check permissions and tenant isolation per role.

optimavo.de

optimavo.de open

Optimavo

Review management for businesses

What it does: Collects reviews from six platforms in one dashboard. An AI analysis shows problems, recommended actions and a comparison with competitors.
What I built: Integration of six review platforms
AI analysis with actions and competitor comparison
Stripe subscriptions
Background jobs via n8n, email notifications, monthly PDF reports
Stack: TypeScript
React
Anthropic Claude
Stripe
n8n

Evidence

6 platforms in one dashboard.

liviton.webflow.io

liviton.webflow.io open

Liviton Realty

Website for a villa agency in Thailand

What it does: The website of a real estate agency for villas in Hua Hin, Phuket and Chiang Mai.
What I built: Listings with status: available, reserved, sold
Featured property, pages for buyers and sellers
Magazine, testimonials and inquiry form
Everything maintained in the Webflow CMS
Context: A marketing website the client maintains on their own.
Stack: Webflow
Webflow CMS
Webflow Interactions

Focus

From the database to the interface

A cross-section of what I build. On the right, the projects each layer is part of.

From the database to the interface
Layer	Content	Einwandfr.ai	Cloora	Optimavo	Liviton
Interface	React, Vite, Tailwind CSS, Recharts, dnd-kit. Webflow with CMS for marketing sites. Technical SEO: structured data, sitemaps, IndexNow. Part of: Einwandfr.ai, Cloora, Optimavo, Liviton	yes	yes	yes	yes
Desktop	Electron for macOS and Windows, with signing, notarization and automatic updates. Part of: Einwandfr.ai, Cloora	yes	yes	no	no
AI	Anthropic Claude, answers from each customer's own knowledge, real-time speech recognition, quality measurement with fixed test questions and a grading model. Part of: Einwandfr.ai, Cloora, Optimavo	yes	yes	yes	no
Payments	Stripe Billing with subscriptions, team seats, usage limits, invoices and EU reverse charge. Part of: Einwandfr.ai, Cloora, Optimavo	yes	yes	yes	no
Integrations	OAuth to HubSpot, Pipedrive, Close, Zoho, Google and Microsoft. Webhooks, REST APIs, automation with n8n. Part of: Einwandfr.ai, Cloora, Optimavo	yes	yes	yes	no
Backend	Node.js with Express, Supabase Edge Functions, Cloudflare Pages Functions. Part of: Einwandfr.ai, Cloora, Optimavo	yes	yes	yes	no
Database and security	PostgreSQL and Supabase with row-level security, roles and permissions, migrations and triggers. Credentials encrypted with AES-GCM. Fail-closed. Part of: Einwandfr.ai, Cloora, Optimavo	yes	yes	yes	no
Operations	Cloudflare, Vercel, Railway, Docker, GitHub Actions. Part of: Einwandfr.ai, Cloora, Optimavo	yes	yes	yes	no

Approach

Four principles

Measure, don’t guess

I back up claims about quality, speed and security. Every test gets a counter-check: I inject the fault on purpose, and the test has to fail.

Try it in the test run above

Fail-closed

What cannot be determined with certainty counts as no. Errors are made visible, not silently swallowed.

User permission

confirmeddeniedundeterminable

ResultAccess: no

AI-assisted, not AI-trusting

I develop with Claude Code. I review every generated line like a stranger's pull request.

Clear communication

Regular written updates on progress, risks and open decisions.

UpdateExample

Progress: Billing with team seats done, tests green.
Risks: The calendar API rate-limits requests. A buffer is planned.
Open decisions: Invoices in German and English, or German only?

Technologies

Tools

Languages: TypeScript
JavaScript
SQL
Frontend: React
Vite
Tailwind CSS
Recharts
dnd-kit
Websites: Webflow (CMS, Interactions)
Backend: Node.js (Express)
Supabase Edge Functions
Cloudflare Pages Functions
Database: PostgreSQL / Supabase (RLS, migrations, triggers)
AI: Anthropic Claude API
AssemblyAI (streaming speech recognition)
Infrastructure: Cloudflare
Vercel
Railway
Docker
GitHub Actions
Payments: Stripe (Checkout, Billing, customer portal, tax)
Testing: Vitest
Node Test Runner
automated probes against real databases