OpenWriterAI Writing SaaS
A full AI writing SaaS built as founder and lead developer: resume builder, proposal generator, AI detector and humanizer, plus a browser extension that assists users as they write online. RAG retrieval over a Supabase vector database, with Lemon Squeezy handling subscriptions and billing.
Screens from the build
The challenge
Freelancers and job seekers spend hours producing resumes and proposals that get filtered out by ATS software or read as generic. The product needed to cover the whole writing workflow, work where people actually write, and run as a real subscription business.
What we did
Built OpenWriterAI as founder and lead engineer on Nest.js and Next.js with LangChain and OpenAI: an ATS-optimised resume builder, an Upwork proposal generator, an AI detector and a humanizer, plus a browser extension that assists inside other sites. RAG over Supabase Vector DB grounds generation in the user’s own material. Lemon Squeezy handles subscriptions, billing and tax as merchant of record.
The outcome
A live SaaS product with a free tier, subscription plans and a browser extension, sold directly rather than built for a client.
By the numbers
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What was built
ATS-optimised resume builder
Structured output that passes applicant-tracking filters.
Proposal generator
Upwork-style proposals from a job post and the user’s profile.
AI detector and humanizer
Multi-engine detection and a rewrite pass to read naturally.
Browser extension
Writing assistance inside the sites people already use.
RAG over user material
Supabase Vector grounds generation in the user’s own documents.
Subscriptions and billing
Plans, trials and global tax handled by Lemon Squeezy.
Technology stack
Technologies that powered this project.
Frontend
Backend
Database & Tools
Development process
Our proven methodology for delivering exceptional results.
Discovery & Planning
Understanding requirements, analyzing scope, and creating a detailed roadmap
1-2 weeks
Design & Architecture
System architecture, UI/UX designs, and technical specifications
2-3 weeks
Development & Testing
Agile development with continuous testing, code reviews, and QA
4-8 weeks
Deployment & Launch
Production deployment, performance optimization, and go-live support
1 week
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