SchemaLens compares SQL schemas in your browser and generates migration scripts instantly. 147 days of public building. 50+ free micro-tools. 51+ SEO pages. 100% client-side. No frameworks, no build step, no dependencies.
npx schemalens-cli diff old.sql new.sql --dialect postgres
MIT licensed. Your schemas never leave your browser.
Real transparency. No vanity metrics.
Everything runs client-side. Your schema never touches a server. Verify it yourself in DevTools → Network. Zero network requests containing your data.
Open the URL and diff in 10 seconds. No install, no signup, no backend. Or run npx schemalens-cli locally if you prefer the terminal.
Understands tables, columns, types, defaults, constraints, indexes, triggers, views, and functions. Not a text diff — it knows that VARCHAR(100) → VARCHAR(255) is a type change, not a deleted line.
Risk score (0–100) with 14 advisor categories. Flags dangerous migrations — column drops, type shrinks, NOT NULL without DEFAULT, primary key removals — before they hit production.
Run locally with npx schemalens-cli. Integrate into GitHub Actions, GitLab CI, and Bitbucket Pipelines. Same engine, same output, no browser required.
Share diffs via base64-encoded URLs. Export to Markdown, PDF, JSON, SQL, Prisma, or Drizzle. Embed a live diff widget on your docs site with an iframe.
147 days of building a dev tool in public. The honest truth.
After 147 days and 51+ tools, we had zero sales. The product worked. The pricing was fair. The problem was simply that not enough people knew we existed. Product Hunt is our answer.
Every micro-tool is a landing page, a keyword opportunity, and a shareable asset. At 51+ tools, we have more free tools than many paid SaaS products have features.
We discovered a critical bug on Day 115: every Pro purchase link on the site was 404. No one reported it because no one was buying. Traffic reveals truth.
The "vibe-coded" criticism from Reddit hurt. Our response: open-source the diff engine, publish the CLI on npm, and document the architecture. Trust is earned, not assumed.
Pre-launch emails, welcome drips, winback campaigns, and newsletter broadcasts are all built and automated. A subscriber who knows the launch is coming is 10x more likely to upvote.
Vanilla HTML/CSS/JS. No build step. No framework. Zero backend for core features. This let us ship 51+ tools and 51+ pages in 147 days without a single deployment failure.
Lifetime Pro. No subscription. 100% margin.
🔒 14-day money-back guarantee · Pay once, keep forever · All future updates included
Hey Indie Hackers 👋
I built SchemaLens because I was tired of reviewing database migrations by eyeballing two SQL dumps. Text diffs of schema files are noisy and miss semantic meaning — is that column renamed or dropped and re-added? Is the type widening safe? Did someone drop an index that a query depends on?
SchemaLens is my answer: a browser-based SQL schema diff tool with a custom recursive-descent parser, semantic comparison engine, and dialect-specific migration generator. Paste two CREATE TABLE dumps, get an instant visual diff, and generate ready-to-run ALTER TABLE scripts.
Privacy: Everything runs client-side. Your schema never touches a server. I can't see your data, and I don't want to. Open DevTools → Network and verify for yourself.
Self-hosting: It's all static files. Clone the repo, open app.html in a browser. The "backend" is air. The engine is MIT licensed and on npm as schemalens-engine.
Monetization: Gumroad license keys. The web tool works without a backend, so hosting is free (Vercel). The CLI is open-source on npm. Revenue is 100% margin minus Gumroad's fee. No ads. No data selling. No VC.
Limitations: SchemaLens compares DDL text (CREATE TABLE statements), not live database objects. It can't connect to your database — that's by design for the browser version. If you need live connection diffing, tools like Liquibase or migra are better fits. SchemaLens fills the "I have two dumps and need to see what changed" niche.
The past 147 days have been a public build marathon — 50+ micro-tools, 51+ SEO landing pages, a CLI, VS Code extension, Chrome extension, GitHub Action, and an open-source engine. All documented in PROGRESS.md.
Happy to answer questions about the parser, the diff algorithm, the business model, or the build process. — Jochen
No signup required. No data leaves your browser.