It's easy to underrate a tool as "simple" as a JSON formatter. But the difference between a good one and a bad one shows up constantly when you're debugging an API response at 1am. Here's what actually matters in a formatter, and how to get more out of the one in Knight DevTools or any similar tool.
Formatting is the easy 20%
Pretty-printing JSON with consistent indentation is table stakes. The more useful 80% is everything around it:
- Validation with a useful error location — "invalid JSON" is useless; "unexpected token at line 42, column 7" saves real time.
- Collapsible nodes — for deeply nested API responses, being able to collapse everything except the branch you care about turns a wall of text into something scannable.
- Type-aware coloring — strings, numbers, booleans, and null visually distinct at a glance, so a bug like a number silently being sent as a string jumps out immediately.
- Minify/beautify toggle — sometimes you need to shrink a payload for a request body, sometimes you need it expanded for reading. One tool should do both.
A common debugging workflow
When an API integration misbehaves, a typical flow looks like:
- Copy the raw response body from your network tab or logs.
- Paste into a formatter to check it's actually valid JSON (a surprising number of "JSON parsing" bugs are actually the server returning HTML error pages or truncated output).
- Collapse unrelated branches to isolate the field you're investigating.
- Check the exact type of the problem field — is that
ida number or a string? Is that boolean actually a boolean, or the string"false"(which is truthy)? - Copy the cleaned, formatted version into your bug report or code comment, so the next person doesn't have to repeat the process.
The "string that isn't a boolean" trap
One of the most common real bugs a formatter surfaces: an API returning "true" (a string) instead of true (a boolean). In JavaScript, if ("false") evaluates to truthy, which silently breaks conditional logic in a way that's genuinely hard to spot without visually distinct type coloring. This single class of bug alone justifies keeping a proper formatter as a daily-use tool rather than eyeballing raw text.
Client-side matters here too
API responses frequently contain sensitive data — auth tokens, user records, internal IDs. A formatter that processes everything in your browser (as ours does) means you're not pasting production data into a third-party server you don't control. For anything touching real user data, that's not a minor detail.
Beyond JSON: the same principle applies elsewhere
The same reasoning extends to our other DevTools — the meta tag generator, the Open Graph previewer, the sitemap and robots.txt generators. Individually each one looks like a small convenience. Together, they remove the friction of "I know what correct output looks like, I just don't want to hand-write it or debug a typo in it." That's the actual value proposition of a good small tool: not doing something you couldn't do yourself, but doing it reliably in fifteen seconds instead of fifteen minutes.