Show HN: StackStats – Analytics tool for Substack writers, runs 100% locally

Hi HN,

I've been writing on Substack for about 5 years with close to 3,000 subscribers. The platform has grown a lot but the analytics have barely changed, and there's still no API support.

I like to explore data, and Substack lets you export some analytics as CSVs from the creator dashboard. I've been doing that for a while, mostly with local scripts, but realized this could be useful to other writers as a simple local tool.

So I built StackStats. A better analytics app for Substack Writers.

You export your CSVs, point it at the folder, and everything populates. Growth sources, engagement scoring, cohort retention, bot-filtered open rates (GoogleImageProxy alone inflated my opens by ~51%), best day/hour to post, and more.

There's an optional AI feature for deeper insights. Totally optional, but why not go with the hype :D. You can use any provider (Claude, GPT-4, Gemini, Groq, OpenRouter) or run Ollama fully offline. BYOK, no lock-in.

Built with Electron and vanilla JS. No cloud, no account, no telemetry. All data stays on your machine.

You can see a live demo with my actual newsletter data here: https://demo.stackstats.app

Happy to answer questions about the app!