Convert JSON to NDJSON
Convert JSON to NDJSON right in your browser. Your file is not uploaded to a server.
How to use it
- Drag your .json files onto the area above, or press "Choose files".
- If options are shown, set them as you like. They appear below the file list.
- Press "Convert". The conversion runs on your device, shows its progress and can be cancelled at any time.
- Press "Download" next to a result. With several results, "Download all as ZIP" gets them in one go.
The formats involved
JSON .json
JSON is a text data format for writing values such as objects, arrays, strings and numbers. RFC 8259 explains that numbers within the range of IEEE 754 binary64 can be expected to be read as the same value by different implementations (section 6).
NDJSON .ndjson .jsonl
NDJSON is a text format that writes one JSON value per line (NDJSON 1.0.0).
What changes in this conversion
- Integers larger than 9,007,199,254,740,991 cannot be stored exactly by JavaScript and may be rounded. When the file contains such numbers, a note is shown with the result.
Limits and things to watch for
- The file size that can be processed depends on your device. The limit for your device is shown in the drop area, and files above it are refused with a message.
FAQ
Is my file uploaded to a server?
No. Conversion happens only inside this browser, and file names, contents and results are not sent to our servers. Some converters download their conversion program (code) the first time you use them; your files are not sent then either. See the privacy page for details.
Can I convert many files at once?
Yes. Select several files and they are processed one after another; save the results one by one or all at once as a ZIP. How much can be handled at once depends on your device memory and is shown on the page.
Sources and check date
- RFC 8259 The JavaScript Object Notation (JSON) Data Interchange Format
section 6: numbers, interoperability within IEEE 754 binary64 · 2026-11-10 - NDJSON - Newline delimited JSON 1.0.0
one JSON value per line · 2026-11-10 - JSON Lines
UTF-8, one JSON value per line · 2026-11-10 - QOI specification 1.0 (qoiformat.org)
14-byte header (magic qoif, big-endian width/height, channels 3|4, colorspace 0|1), 8-byte end marker, un-premultiplied alpha · 2026-11-10 - Netpbm: PPM format specification
Magic numbers P3 (plain) / P6 (raw); Maxval below 65536; 2 bytes per sample when Maxval >= 256 · 2026-11-10 - Microsoft Learn: Bitmap Header Types
BITMAPINFOHEADER / BITMAPV4HEADER; RedMask/GreenMask/BlueMask valid with BI_BITFIELDS; bottom-up rows padded to 4 bytes · 2026-11-10 - WebP Container Specification
ANMF chunk (blending/disposal bits), VP8X flags, ANIM loop count · 2026-11-10 - POSIX pax / ustar (Open Group Base Specifications Issue 7)
pax interchange format, extended header records (path, mtime, size) · 2026-11-10 - EPUB 3.3 (W3C Recommendation), OCF ZIP container
4.2.2 reserves the file name mimetype; 4.3 ZIP requirements (section 4.3 body not read) · 2026-11-10 - W3C: WebVTT: The Web Video Text Tracks Format (Candidate Recommendation Draft 20 May 2026)
File body: UTF-8, MIME text/vtt, optional BOM, "WEBVTT" line; timestamp: hours optional (required if non-zero), mm:ss.ttt with FULL STOP; cue text may contain character references · 2026-11-10 - GitHub Flavored Markdown Spec: tables (extension)
header row, delimiter row, pipe escaping · 2026-11-10 - Java SE 21 java.util.Properties
load(): line continuation, comments, escapes; ISO 8859-1 and Unicode escapes · 2026-11-10 - python-dotenv README (file format)
export directive, quoting, allowed escape sequences, comments · 2026-11-10 - RFC 7519 JSON Web Token
JWT structure, registered claims exp / nbf / iat · 2026-11-10 - RFC 4648 Base16, Base32, Base64 Encodings
Base64, Base64URL, Base16 · 2026-11-10 - RFC 3986 URI Generic Syntax
percent-encoding, reserved and unreserved characters · 2026-11-10 - National Institute of Korean Language: Romanization of Korean
basic principles, transcription system, special provisions and the example words used in our tests · 2026-11-10 - HTML Standard: named character references
entity list incl. legacy names without semicolon · 2026-11-10 - Unicode Standard Annex #15 Normalization Forms
NFC, NFD, NFKC, NFKD · 2026-11-10
Date we opened the original documents ourselves: 2026-11-10. Specifications can change, so read the original again before anything important.