DEV3 GST and VAT Calculator — Source Code (React + Tailwind)

Source code of the DEV3 GST and VAT Calculator, tax add and remove calculations in integer minor units, with Indian GST slabs and CGST/SGST/IGST splits plus a list of common VAT rates.

Download: buy a licence and the ZIP is waiting in Account → Downloads. Try it live: https://dev3.tech/tools/gst-vat-calculator shows the finished tool running.

What is in the download

• A standalone Vite + React + TypeScript + Tailwind CSS project: src/tool holds the tool, shared pieces sit beside it
• package.json with exact versions plus a lockfile, so npm ci works
• README.md (run, build, embed in Next.js or plain React) and an MIT LICENSE

What the code does

• Add tax or extract tax from a gross amount
• GST split between central, state and integrated tax
• VAT rate presets by country
• Rounding done in minor units

Tech stack

React 19, TypeScript, Vite, Tailwind CSS 4.

Install and customise

The How to install and How to use tabs list the steps. In short: unzip, npm ci, npm run dev, then copy the tool folder into your own app if you want to embed it.

Good to know

• A browser-only tool: there is no backend or database in the code.
• Tax rates change; verify every rate against your tax authority before relying on a result.