If you write software, you deal with JSON. It's in your API responses, your config files, your logs, your package.json, your test fixtures — everywhere. And yet most developers are still bouncing between five browser tabs just to format a blob, diff two payloads, or figure out why JSON.parse is throwing a tantrum.
Here are 10 tools that actually earn a place in your workflow, from quick browser utilities to CLI powerhouses.
1. jq — the command-line JSON Swiss Army knife
If you touch JSON in a terminal, jq is non-negotiable. It lets you filter, map, and transform JSON the way grep/sed/awk handle plain text.
curl -s https://api.github.com/repos/stedolan/jq | jq '.stargazers_count'
It's especially powerful in scripts and CI pipelines where you need to extract a value from an API response without spinning up a full parser.
2. Postman
Postman is the default choice for exploring and testing APIs, and a big part of that experience is its built-in JSON handling — pretty-printing responses, letting you write test assertions against JSON paths, and generating code snippets in a dozen languages from a single request. If your team collaborates on API contracts, its shared collections are hard to beat.
3. JSONLint
Sometimes you don't need anything fancy — you just need to know why a JSON payload is invalid. JSONLint validates and formats JSON in the browser, pointing at the exact line and character where things break. It's the tool you paste malformed JSON into at 2am when a client insists their payload is "definitely valid."
4. VS Code with the JSON language service
It's easy to forget that VS Code ships with a genuinely good JSON tool built in. Syntax highlighting, schema validation, auto-formatting, and — if you attach a $schema or a .vscode/settings.json schema mapping — real autocomplete for deeply nested config files. For anyone editing tsconfig.json, GitHub Actions workflows, or OpenAPI specs by hand, this alone saves a lot of guesswork.
5. JSON Crack / JSON visualizers
Nested JSON with a dozen levels of arrays and objects is nearly impossible to reason about as flat text. Visualizers like JSON Crack render your JSON as an interactive node graph, which makes it dramatically easier to understand the shape of an unfamiliar API response or a deeply nested config.
6. Online JSON diff tools
Comparing two JSON payloads by eye is a recipe for missing a single changed field buried three levels deep. A dedicated JSON diff tool (there are several solid free ones online) highlights structural and value differences directly, which is invaluable when debugging "why did this API response change between environments."
7. json2csv / json-to-table converters
Not everyone downstream of you speaks JSON. Product managers want a spreadsheet. A converter that turns an array of JSON objects into CSV (or a clean table) saves you from writing a one-off script every time someone asks "can you just send me this as Excel."
8. Insomnia
Insomnia is Postman's leaner cousin — a REST/GraphQL client with strong JSON body editing, response filtering via JSONPath, and environment variable support. If Postman feels heavier than your workflow needs, Insomnia is worth trying.
9. Python's json module + jsonschema
For anything beyond quick inspection — validating that incoming payloads conform to a contract, generating fixtures, or writing tests — Python's standard json module paired with the jsonschema package is a reliable combo. It's especially handy for validating API responses against an OpenAPI-derived schema as part of a test suite.
import json, jsonschema
data = json.loads(raw_response)
jsonschema.validate(instance=data, schema=my_schema)
10. Browser-based formatter/validator/converter suites
Finally, for the day-to-day stuff — formatting a minified blob, validating structure, converting JSON to YAML or XML, generating TypeScript interfaces from a sample payload — a solid all-in-one browser toolkit saves a lot of context-switching. I've been building SamToolKit for exactly this: a set of free, browser-based developer tools (JSON formatter, validator, converters, and more) where nothing you paste ever leaves your browser — everything runs client-side, so there's no server round-trip for your data. Worth a look if you want a no-signup, privacy-friendly option for quick JSON tasks.
Wrapping up
You don't need all 10 of these in daily rotation — pick two or three that match how you work. A CLI person should live in jq. An API-heavy team should standardize on Postman or Insomnia. Anyone doing config-heavy work should lean on VS Code's built-in JSON support. But knowing this toolbox exists means you're never stuck fighting a JSON payload with nothing but console.log and hope.
What's your go-to JSON tool that didn't make this list? Drop it in the comments.
