Job Overview

Content Sieve is an AI-powered Chrome extension (Manifest V3) that filters web content by topic across any website, using OpenAI's API via a Cloudflare Worker proxy to intelligently distinguish genuine topic matches from false positives. The extension is live on the Chrome Web Store with a working free/premium tier model and Stripe subscription billing already in place. We are looking for a developer to help extend its capabilities, improve filtering accuracy, and build toward a more polished product.

Responsibilities

• Develop, test, and deploy updates to a Manifest V3 Chrome extension using vanilla JavaScript, working across content scripts, background service workers, and the popup UI.
• Improve and extend the core AI filtering logic, including the keyword-first gate and dual-model routing between GPT-4.1-nano (free tier) and GPT-4.1-mini (premium tier).
• Maintain and enhance the Cloudflare Worker back end, including the /api/check-content, /api/validate-key, /api/checkout, and /api/stripe-webhook endpoints.
• Work with Cloudflare KV namespaces for licence key storage and free-tier daily cap enforcement.
• Extend or improve the Stripe integration, including checkout session creation, webhook handling, and licence key generation on successful payment.
• Improve DOM traversal logic in the content script for more reliable card detection across deeply nested React and Next.js page structures.
• Maintain and improve the popup UI, built in HTML, CSS, and vanilla JavaScript.
• Manage session caching logic and client-side rate limiting (token bucket) to minimise unnecessary AI calls.
• Use Git and GitHub for version control throughout.
• Document architectural decisions and deployment steps clearly for ongoing reference.
• Help build the Android and iOS version

Experience

• Demonstrable experience building Chrome extensions using Manifest V3, including content scripts, background service workers, and the Chrome messaging API.
• Strong proficiency in vanilla JavaScript, including asynchronous patterns, chrome.storage.sync, and browser extension APIs.
• Hands-on experience with Cloudflare Workers and Wrangler, including KV namespace management and secret configuration.
• Familiarity with the OpenAI Chat Completions API and prompt design for classification tasks.
• Experience integrating Stripe, including checkout sessions, webhook verification (HMAC-SHA256), and subscription lifecycle events.
• Solid understanding of HTML5 and CSS3 for extension popup and options UI work.
• Version control with Git and GitHub is essential.
• Experience with DOM traversal and content manipulation across diverse page structures, including React and Next.js sites, is a strong advantage.
• Prior experience shipping a published browser extension is strongly preferred.
• A Computer Science or related degree preferable but not compulsory.

Before You Apply

We ask that all candidates install Content Sieve from the Chrome Web Store or www.veriscope.digital and spend a few minutes using it before submitting an application. We're looking for a brief professional assessment alongside your application: what works well, what doesn't, and where you see the clearest opportunities for improvement — whether in filtering accuracy, UI, performance, or architecture.

This isn't a test with a right answer. It tells us how you think about an existing codebase and a real product, and it means any conversation we have from the first message is grounded in direct experience of what you'd be working on.

The extension is free to install. Find it at the Chrome Web Store or www.Veriscope.Digital

Pay: £15.00-£30.00 per hour

Work Location: Remote