Anvil Tools
JSON Formatter & Validator
Pretty-print, minify, and validate JSON directly in your browser.
Open tool →CSV to JSON Converter
Parse comma-separated data with quoted fields, escaped quotes, commas, and line breaks, then export valid formatted JSON.
Convert CSV to JSON
Keep identifiers and quoted fields intact
Try the comma-separated sample with the header option enabled. The first identifier stays 001, the quoted comma belongs to the name, the blank note becomes an empty string, and the doubled quote becomes one quote in the second note.
| Input or check | Expected result or decision |
|---|---|
| 001,"Amina, Ali", | {"id":"001","name":"Amina, Ali","note":""} |
| 002,Omar,"He said ""hi""" | {"id":"002","name":"Omar","note":"He said \"hi\""} |
| Tab- or semicolon-separated source | Export comma-separated CSV first; there is no delimiter selector. |
| Quoted newline inside "First line\nSecond line" | The newline remains inside one field; it does not start another row. See the downloadable input and expected JSON. |
| id,id followed by 001,002 | Rejected: Header names must be unique. |
Download the quoted-newline CSV ยท Compare the expected JSON
How it works
- Paste comma-separated data encoded according to common CSV quoting rules.
- Keep the header option enabled to produce objects, or disable it to produce arrays.
- Rows with a different number of columns are reported instead of silently losing data.
Common uses
- Turning spreadsheet exports into API fixtures.
- Converting a small data table for JavaScript.
- Checking quoted commas and multiline fields before import.
Your input stays in this browser. Nothing entered into this tool is sent to the Anvil Tools server.
A practical walkthrough
- Paste name,city followed by a new line containing Anvil,Lahore. Enable the header option to use the first row as property names.
- Inspect the generated objects and make sure every row has the same number of columns before using the JSON.
- Copy the JSON or download converted-data.json. Check headers, row counts and string values against the source CSV.
Tips for a reliable result
Quote fields containing commas and double any quote inside a quoted field. Fix inconsistent rows in the source instead of silently discarding data.
What to use next
These tools open separately; inputs are not transferred.
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Compare two texts line by line and highlight additions and removals.
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Convert text to upper, lower, title, sentence, camel, snake, and kebab case.
Open tool →Base64 Encoder & Decoder
Convert text to Base64 and back, entirely in your browser.
Open tool →How this tool handles your data
CSV text is parsed in your browser and is not uploaded to an Anvil processing server.
Known limitations
The parser targets common comma-delimited CSV. Delimiter variants, inconsistent row widths, spreadsheet formulas, encodings, and very large datasets need separate checks.
Related guide and Lab test
Questions and troubleshooting
Which CSV features are supported?
Fields may be quoted, contain commas or line breaks, and escape a quote as two consecutive quote characters. UTF-8 text and CRLF or LF line endings are supported.
Are numbers converted automatically?
No. CSV has no reliable type metadata, so values remain strings to avoid changing identifiers, leading zeros, dates, or large numbers.
When CSV rows are rejected
This parser uses commas; it has no separator selector. Check quoted fields, header uniqueness, and the column count in each row. Start with the header and one failing row to isolate the issue. Converted values remain strings, so check numeric or boolean requirements in the receiving application.
Why are leading zeros important?
Values such as postal codes or account identifiers may look numeric but need to remain text. Inspect the resulting JSON types before importing the data into another system.
Can I paste tab-separated spreadsheet data?
The parser expects comma-separated values. Export or prepare CSV first, quote fields that contain commas, and use consistent column counts.
Read the practical guide
Debug API Data with JSON, Base64, and Browser Tools
Work through JSON types, encoding, URL components, JWT claims, hashes, CSV conversion, and timestamps with small reproducible examples.
See the recorded experiment
CSV Edge Cases: Quotes, Unicode, Newlines, and Blank Fields
Thirteen recorded CSV conversions show preserved strings, rejected headers, quoted newlines, and a semicolon-delimiter trap.