How to open JSON
JSON is plain text and you can open it with anything. The real question is how to read it when the file holds ten thousand records and four levels of nesting.
Options by task
| Task | Tool | Caveats |
|---|---|---|
| Take a peek at a small file | browser, Notepad++, VS Code | formatting and highlighting, but no search by value |
| Check that it is valid | any validator, an editor with highlighting | online validators make you paste the content — not suitable for work data |
| Find records by a condition | a table with filters | needs a flat form — nesting is expanded into columns |
| Count and group | a table or an SQL tool | an editor cannot do this at all |
| Process regularly | a script, jq | needs skill, but is repeatable |
Why a tree is inconvenient
Browsers and editors show JSON as a tree: you can collapse and expand nodes and search for text. For a file with twenty records that is enough.
Then the problems begin. You cannot sort, you cannot filter by a condition, you cannot add up a column, you cannot compare two exports. All of these are operations on a table, and a tree is not one until it is unfolded.
What “unfold into a table” means
Three steps, each with its own choice:
- Find the array with the data. In an API response it usually sits under a key next to metadata.
- Build the columns as the union of the keys of all elements — otherwise fields that the first record lacks get lost.
- Expand nesting into columns with dot notation. The details are in Nested JSON to a flat table.
Be careful with online services
Most online JSON viewers ask you to paste the content into a field on the page or upload the file to a server. For a tutorial example that is fine; for a work export it is not: JSON from a company system usually carries personal data, contracts or internal identifiers.
Parsing in the browser removes the question: the file is read on your device, there are no network requests carrying its content, and you can verify that in the developer tools.
FAQ
Why does my browser show JSON as plain text without highlighting?
It depends on the Content-Type header. If the server sent text/plain, the browser will not turn on its JSON viewer.
What if the file will not open because of a parse error?
Then the JSON is invalid. A common cause is concatenated API responses: that is really JSON Lines and has to be read line by line. See JSON Lines (NDJSON).
Is there a size limit?
For regular JSON, yes: it is parsed in full. Above 512 MB we honestly refuse instead of hanging the tab. Details in Large JSON files.
Free for personal use. Your file is not uploaded to a server. Windows version — 3.5 MB, no installation: details. Organizations: license.