Pixy Plugin Platform
A full commercial SaaS product for Autodesk Revit: 20+ geometry, AI and productivity tools delivered as a Revit add-in, backed by a custom licensing server, a payments pipeline, a cloud storage layer and an automated growth engine. It ships to paying customers worldwide across Revit 2025–2027.
Overview
What Pixy actually is
Most Revit “plugins” in a portfolio are a script and a button. Pixy is a product: a desktop add-in that people pay for, a licensing system that decides whether it runs, a payments pipeline that provisions it, a cloud tier that stores what it produces, and a growth engine that sells it. Each of those is a separate engineering problem with its own failure modes.
This section documents the production system as deployed — the architecture, the threat model, and the reasoning behind each decision. Every stage below is a page of its own.
How this was built
I own Pixy end-to-end as product architect and engineering director. The implementation is AI-assisted: I specify the architecture, make every product, pricing, security and infrastructure decision, direct the build, and verify and ship each piece to production myself. The judgment calls documented here — threat modeling, licensing strategy, pricing, data-safety constraints, release process — are mine, and every change was reviewed, tested and deployed under my control.
Architecture
System at a glance
Pixy is three tiers plus two commercial subsystems.
| Tier | What it is | Stack |
|---|---|---|
| Desktop add-in | The Revit plugin — tools, UI, licensing client, AI client | C# / .NET 8 & .NET 10, WPF, Revit API, obfuscated |
| License server | Validation, payments, entitlements, cloud APIs | Node.js / Express on Render, Supabase Postgres |
| Website | Marketing site, checkout, PixyCloud web app, 360 viewer | Static site on Netlify, Paddle.js |
| Payments | Checkout, subscriptions, webhooks | Paddle Billing |
| Cloud storage | AR models, 360 panoramas, publishing | Cloudflare Worker + R2 (files.pixyplugin.store) |
Supporting services: Resend for transactional email and campaigns, a Telegram admin bot acting as support desk and ops alerting, and a hardened AI proxy that brokers every third-party AI request so no provider API key ever touches a customer machine.
Deep dives
The six stages
The Revit Add-in
One obfuscated DLL across Revit 2025–2027, and the tool suite it ships.
Licensing & Anti-Piracy
Signed client–server protocol, hardware binding, and an offline policy that never locks out a paying user.
The License Server
Validation, Paddle payments, self-healing migrations, and a continuously-tested security posture.
AI Suite, Pixels & Cloud
A credential-safe AI proxy, a metered pixel economy, and R2-backed cloud publishing.
Growth Engineering
Per-recipient signed offers that turn the customer base into expansion revenue without leaking a discount.
Testing & Release Safety
Behavioural tests, CI that fails closed on leaked secrets, and post-deploy verification.
Highlights
Engineering problems worth calling out
-
Making one obfuscated DLL run across every Revit 2025–2027 build without recompilation, via multi-targeting, an assembly-resolve shim and a post-build reference-patcher. -
A licensing system that resists piracy yet never locks out a paying user offline — pinned-key signature verification, hardware binding that doubles as the local-storage encryption key, dual fail-closed / fail-open gates, and server-time-anchored offline grace. -
Closing an RLS privilege-escalation oracle exploitable with a public anon key, with a migration that verifies its own success and aborts otherwise. -
A credential-safe AI proxy that re-derives secrets per redirect hop, fixing a header-leak class that the default HTTP client would have shipped. -
Leak-proof discount mechanics using per-recipient signed tokens and idempotent, in-place license mutation instead of coupon codes. -
Turning Revit’s single-threaded, context-bound API into a host for modeless, previewable, async tools without freezing the UI or crashing the host.
Stack
Tech stack
C#, .NET 8 & .NET 10 (Windows), WPF, WinForms, Revit API 2025–2027, Obfuscar, SharpGLTF, VoronoiLib, SharpVectors, QRCoder, WMI/DPAPI, AES-256-GCM, RSA.
Node.js (pinned major), Express, PostgreSQL (Supabase) via pg, RS256/RSA JWTs, rate-limiter-flexible + Redis, Helmet, custom CORS.
Render (backend), Netlify (site), Cloudflare Workers + R2 (cloud storage), Paddle Billing (payments), Resend (email), Telegram Bot API (support/ops), GitHub Actions (CI).
AI providers, all server-brokered: fal.ai, Tripo3D, Hi3D, OpenRouter, Google Gemini / Generative Language.