FormatEx

Overview

FormatEx is a production SaaS platform that exposes a dead-simple REST API for compiling LaTeX documents into PDFs. Think of it as "the Stripe of LaTeX compilation" — developers send a .tex file, get a PDF back, and never touch TeX Live again.

The platform is live at formatex.io.

Architecture

A Docker Compose stack on an Oracle VM orchestrates five services:

• Nginx — reverse proxy on port 9002
• latex-api — Go/Gin HTTP server (port 8080)
• latex-worker — Go/Asynq background worker (2 replicas) for async compilation jobs
• latex-postgres — PostgreSQL 16 storing users, API keys and compilation logs
• latex-redis — Redis 7 backing the Asynq job queue and rate limiter
• latex-frontend — Next.js 16 dashboard (port 9003)

Tech Stack

Backend

• Go 1.25 + Gin framework
• PostgreSQL 16 with pgx and connection pooling
• Redis 7 + Asynq for async job queuing
• TeX Live — pdflatex, xelatex, lualatex, latexmk
• Auth: JWT (HS256, 24 h) for users; SHA-256 hashed API keys for compilation
• Billing: Polar.sh (checkout, portal, webhooks — Merchant of Record)
• Deployment: Docker Compose on Oracle VM

Frontend

• Next.js 16 App Router (all use client)
• React 19 + TypeScript 5 strict
• Tailwind CSS v4 + shadcn/ui
• Framer Motion 12 animations
• TanStack React Query 5 for server state
• React Hook Form 7 + Zod 4 for form validation

Key Features

• Multi-engine compilation: pdflatex, xelatex, lualatex, latexmk — plan-gated
• Async jobs: heavy compilations are queued via Redis/Asynq; results polled or streamed
• API key management: create named keys, revoke anytime, raw key shown once (stored as hash)
• Plan enforcement: per-plan compilation limits, engine access, timeout and file-size caps — hard block on Free, soft block on paid
• Usage metering: every compilation logged (engine, status, duration, input size)
• Billing portal: Polar.sh checkout + customer portal wired to plan upgrades/downgrades via webhooks
• Admin panel: user management, plan assignment, usage inspection

Plans

Security

• API keys stored exclusively as SHA-256 hashes; raw key never persisted
• Compilation files are ephemeral — deleted immediately after the response is sent
• User LaTeX content is never logged
• JWT expiry + auto-logout on 401 on the frontend