CSV to JSON moves values, not the whole workbook
Developers need JSON when a spreadsheet has to go into an API or a script.
The header row becomes keys and each following row becomes an object.
Dates and extra sheets after CSV to JSON
The CSV must have a header. Cells stay strings unless they are plain numbers.
A related step, if you still need one, is JSON to CSV.
CSV to JSON without the extra promises
CSV to JSON sits on this site because CSV and JSON are not interchangeable, even when they look similar in a file list. Developers need JSON when a spreadsheet has to go into an API or a script. Mail merges, databases, and Google Sheets imports are typical CSV jobs. Developers convert JSON when a payload must become a sheet, XML, or CSV.
The header row becomes keys and each following row becomes an object.
Read this about CSV before you upload
CSV is one table in text: a row per line, commas between cells. Databases and import forms accept it. A comma inside a name splits one column into two unless the field is quoted. Extra sheets disappear.
Keep the workbook. CSV is not a backup of formulas.
Read this about JSON before you send the download
The download has to be JSON, because that is the format the next step named. Developers convert JSON when a payload must become a sheet, XML, or CSV. A list of similar objects maps cleanly to rows.
This is not encryption. Do not paste passwords or live tokens.
Keep, check, then delete
People lose time when they convert before they know which rule failed. Size, pixel dimensions, codec, font encoding, and layout are different rules. CSV to JSON only addresses the CSV to JSON step. Developers need JSON when a spreadsheet has to go into an API or a script. The header row becomes keys and each following row becomes an object. The CSV must have a header. Cells stay strings unless they are plain numbers. The file stays in your browser and is not uploaded. The limit is 100 MB. Keep the original until the download has been opened in the program that will use it. Do the test with a short or simple file first when the real file is large. A one-page PDF, a single photo, or a one-minute clip will show you whether the output is the kind of file you needed. After that test looks right, run the real file once. Keep both the CSV original and the JSON download until the receiving person or the upload form accepts it. Spreadsheets break at quiet places: a second sheet, a date that changed, a leading zero that vanished, a comma inside a name. After CSV to JSON, open the result in a text editor as well as Excel. Excel guesses types and hides the delimiter. The workbook you calculated in is still the master.
Here is the decision for CSV to JSON. You start with CSV and you stop when a real program accepts JSON. Almost every data tool can read a simple CSV. Nested lists of unknown length will not become one tidy sheet. If those two sentences describe a tradeoff you do not want, do not convert. Renaming the extension by hand will not do this job. Running the tool twice on its own output will not do it either.
The CSV must have a header. Cells stay strings unless they are plain numbers.
A related step, if you still need one, is JSON to CSV.
Other jobs start from the homepage, where each tool is named for the conversion it actually does.