Overview
PressWax is a subscription SaaS that turns written words into a finished song — vocals, instrumentation, and cover art. A user types a single sentence, or pastes full lyrics, and gets back a mastered track. Built end to end: product, billing, infrastructure, and visual design.
The Challenge
Generative audio models are slow and awkward to call directly. A three-minute track takes far longer than a normal HTTP request will stay open, generation occasionally fails mid-flight, and every attempt costs real money — so the accounting has to be exact. A consumer product also has to handle payments, sales tax, refunds, and cancellations correctly from the very first customer, not eventually.
What I Built
- Asynchronous generation pipeline — jobs run in a background worker and the finished audio arrives by webhook from the inference provider, because synchronous calls get dropped after roughly sixty seconds. Local development falls back to a blocking path so the same code runs without a public callback URL.
- Credit ledger — every grant, purchase, refund, and debit is an immutable signed transaction tied to the song and payment session that caused it, so any balance can be rebuilt from history rather than trusted as a running total.
- Full Stripe integration — hosted checkout, customer billing portal, subscription lifecycle kept in sync through webhooks, products and prices addressed by lookup key instead of hardcoded IDs, and tax codes configured for Stripe acting as merchant of record.
- Content moderation layer that rewrites prompts before they reach the model, alongside separate services for lyric writing, title generation, and cover art.
- Song Board — an opt-in public gallery with an admin review queue, so submitting a track is a request rather than an automatic publish.
- Vintage record-label interface — a deliberate move away from the default look of AI products, built on press-sheet typography, paper texture, and a physical-media metaphor.
Results
Went from concept to a live, payment-taking product in a single build cycle. The first real transaction was verified end to end: subscription checkout, webhook-granted credits, refund, and cancellation syncing back to local state. Two production issues surfaced during that test and were fixed the same day — exactly what a live-money dry run is for.
Tech Stack
Python, Django 6, PostgreSQL, Stripe, Gunicorn, nginx, Let's Encrypt, Pillow, and DeepInfra for audio generation.