Redline: Contract review for freelancers

Inspiration

Most freelancers do not have a lawyer on call. A vague brief or a missing kill fee clause looks harmless until a client cancels mid-project or scope quietly triples. Redline exists because catching that before signing should not require legal training, just a paste box.

What it does

Redline takes a pasted freelance contract, brief, or work agreement and marks it up the way a human editor would: risky clauses get highlighted directly in the document, color-coded by severity, with a plain-English explanation of what is wrong and a suggested safer phrasing. An overall risk score and one-line summary sit at the top so the freelancer knows, at a glance, whether this is worth a closer look or a hard pass.

How we built it

The frontend is Next.js with a custom paper-and-ink design system meant to evoke real contract markup rather than a generic "AI tool" look. The backend is a single API route that sends the contract text to an LLM with a structured prompt: the model is required to return exact, verbatim excerpts from the input alongside each flag, which is what lets the app place highlights precisely inside the original text rather than just listing issues in a separate report, and also i used an AI coding assistant to help scaffold and build the app quickly.

Challenges we ran into

Getting the model to return exact verbatim substrings (not paraphrased ones) took prompt iteration, since even small rewording breaks the string-matching needed for inline highlighting. Keeping the app stateless also meant designing the whole flow around a single paste-to-result loop instead of leaning on a database.

Accomplishments that we're proud of

A working end-to-end flow, built solo, that turns a real pain point into something demoable in under a minute: paste text, watch it get marked up live.

What we learned

A lot

What's next for Redline

-Optional history/dashboard for freelancers tracking multiple clients -Support for uploading PDF/DOCX contracts, not just pasted text -A browser extension that flags risky language directly on platforms like Upwork or client portals before a contract is even downloaded

Built With

• geminiapi
• git/github
• next.js
• react
• tailwindcss
• typescript
• vercel