I Built a JSON Formatter After the Original Started Injecting Ads — Here's What I Learned

#opensource #softwaredevelopment #tools #webdev

A few months ago, the most popular JSON formatter Chrome extension (2M+ users) was sold. The new owners immediately closed the source, injected affiliate ads, and started tracking user
geolocation.

HN exploded. Developers fled. Five open-source alternatives appeared within a year.

But here's the thing that bothered me: all of them are free, and none of them have a business model.

This is exactly how we got here. A maintainer burns out, sells to the highest bidder, and 2 million users wake up to ads in their browser. The cycle just repeats.

So I built ClearJSON (https://wayknow.tech/clearjson.html). Not because the world needed another JSON formatter — but because it needed one that wouldn't betray its users.

What makes it different

100% local, verifiable in DevTools. Open the Network tab — there's nothing. Never connects to a server, never sends data anywhere. I can't track you even if I wanted to.

Handles 100MB+ JSON files without freezing. Every free alternative calls JSON.parse() on the main thread. That works fine at 2MB, not at 100MB. ClearJSON does the parsing in a Web Worker so
the browser stays responsive. This was the hardest part to build and the reason most alternatives skip it.

JWT auto-decoding. Half the reason I open JSON is to inspect JWTs. Click a token and it decodes the header + payload inline.

MIT license. Even if I disappear tomorrow, anyone can fork it. The license actually protects users this time.

The business model question

I charge $29 one-time for Pro (large files, JWT, exports, more themes, custom shortcuts). The free tier has everything most people need.

A few people have asked: "Why not just make it free? There are five free alternatives."

Because "free" is how the last one got sold. A one-time purchase with no recurring server costs means there's no incentive to sell out. No investors to please, no data to monetize. Just a
tool that works.

The MCP server (npx -y clearjson-mcp) is also MIT licensed — so AI agents can format and validate JSON directly, including large files that would crash other MCP tools.

What I'd do differently

Start marketing before shipping. I built the whole thing, launched, and then started thinking about distribution. Should have been building an audience in parallel.
The "betrayal" story is a hook, not a business. People upvote the drama, but they don't automatically buy the product.
CWS organic discovery is slow. Without reviews and installs, you rank on page 10. External traffic (blog, Reddit, HN) is the only way to bootstrap.

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