Internal Tools Developer - GCS Portal (Vanilla JS + Supabase)

About GCS We're Global Computer Sales GCS - a B2B and e-commerce computer hardware company. We sell direct to wholesale buyers and end users, and we run a busy Amazon FBA business across multiple seller accounts. Roughly 30 people. Real revenue, real complexity, no marketing fluff. What we've built Over the last few months we built an internal company portal - gcs-opsportal.vercel.app - that pulls live data from Google Sheets, Sellerboard Amazon analytics, and Supabase, and gives the team one place to see sales, finance, ops, commission, and tooling info. It's a real product the team uses every day, not a demo. It looks polished think Mercury / Linear / Stripe aesthetic dark theme, refined typography, command palette search, real charts, snappy navigation and it works. But there's a lot still to build, and I'm out of nights. What you'd do This is a generalist role. The right person comfortably bounces between three modes depending on the week: Builder mode - extend the current vanilla HTML/CSS/JS + Supabase system. New pages, new widgets, new integrations. You'll respect the existing patterns instead of rewriting them. Data plumber mode - wire up more data sources: Slack ingestion, QuickBooks A/R, additional Sellerboard reports, automation. Google Sheets API, Google Apps Script, Supabase functions. Modernizer mode long term optional - over months, if it makes sense, propose and execute a migration to a framework probably Next.js or Astro. I'm open but not in a rush. Don't pitch a rewrite week one. The stack Frontend: vanilla HTML/CSS/JS no framework right now, Chart.js, Lucide icons Backend: Supabase Postgres + Auth + Row Level Security Hosting: Vercel auto deploys from GitHub main branch Data: Google Sheets API read only sources, Google Apps Script Sellerboard email to Sheets router Auth: Supabase email/password, per user profiles with manager role gating Shared design system: polish.css + portal-shell.js Cmd+K palette, view transitions, period state, Chart.js theming Who I'm looking for Must haves: Strong vanilla JS / CSS / HTML. No framework needed for this job, but you should be fluent enough to write clean, modular code without one. Real Supabase or Postgres experience. You can write RLS policies, design a schema, and you know why the service_role key never goes in client code. Frontend taste. I'm not a designer but I know good when I see it. If your portfolio looks like 2014, this isn't a fit. Async, written communicator. Email and short check ins, not video calls. English fluent enough to read product copy and write it back. Nice to haves: Google Sheets API + Apps Script experience Slack API we want to surface important Slack messages into the portal Vercel + GitHub Actions Amazon Seller Central / Sellerboard familiarity huge bonus Comfort writing SQL migrations that don't blow up on existing data What I do NOT want "Let me rewrite this in your framework" as your first message. The vanilla approach is intentional. We can talk about migration after you've shipped real features in the current system. Agencies subcontracting through Upwork. I want the person actually doing the work. Devs who disappear for a week without saying anything. Pixel pushers who can't think about data. Anyone who needs me to write specifications for every task. I'll describe what I want; you figure out how. How this works Hourly. Start at approximately 5 to 10 hours/week. Scale to 15 if it's clicking. Pay rate: open. Send me your number. I'll pay top of market for someone I trust; less if I'm taking a risk. Weekly async check in Slack or email. Show me what shipped, what's blocked, what's next. 90 day trial. First 30 days is a small fixed scope project we agree on up front. If it goes well, we go ongoing hourly. NDA before I share credentials or repo access. Standard, simple, mutual. Your first 30 days paid trial scope To prove the working relationship, your first project is one of these your pick after seeing the repo: Build a Slack ingestion job: messages reacted with the pushpin emoji in our Slack get surfaced on the portal home page. Schema is already in place; the data pull + scheduled job aren't. Ship a /vendors/ rolodex page searchable table of suppliers, contacts, notes, with manager only edit. Integrate QuickBooks A/R aging into our /financial/ page we have read only API access. End of 30 days, I expect: shipped feature, polished, in production, plus a 1 pager retrospective on what you learned about the codebase and what you'd improve. **How to apply** Don't write me a cover letter. Send me three things: Links to 1 to 3 real things you've built. Not Figma mockups. Live URLs preferred, GitHub OK. Your honest take on this kind of stack what would you change about the vanilla JS approach, and what would you leave alone? Your hourly rate, your time zone, and your weekly hours availability. If your message reads like ChatGPT wrote it without you in the loop, I'll skip you. If you tell me something interesting about a portal style product you've worked on, you go to the top of the pile. Looking forward to it