NDJSON / JSON Lines Formatter
NDJSON / JSON Lines Formatter: Splits newline-separated stream, validates each individual line as independent JSON, and pretty-prints array.
About this ndjson / json lines formatter
NDJSON / JSON Lines Formatter — browser-based utility.
How this tool works
Implements client-side NDJSON / JSON Lines Formatter operations. Splits newline-separated stream, validates each individual line as independent JSON, and pretty-prints array specifically designed for a data engineer formats and validates a stream of newline delimited json (ndjson) event log lines.
- Lexical Scanning: Scans the input stream character by character, identifying string literals, escape sequences, numbers, and structural delimiters without converting numeric tokens to native floats.
- Syntax Validation & Invariant Checking: Enforces RFC 8259 syntax constraints, verifying matching braces, balanced brackets, unescaped control characters, and duplicate key collision detection.
- AST Assembly & Structural Transformation: Constructs an immutable memory tree representation, applying structural indentation, key alphabetical sorting, or schema-mapped transposition.
- Serialization & Diagnostic Formatting: Emits formatted, color-coded, or minified text with byte-length calculation, structural nesting depth metrics, and RFC-compliant line terminators.
Worked example
Scenario: Format two independent JSON Lines records.
Sample input:
Processing: Ignore no nonblank records here; parse each line independently and prefix its one-based line number.
Illustrative output:
Limits and verification
Fails with descriptive line and column diagnostics when encountering unquoted object keys, single-quoted strings (in strict JSON mode), trailing commas (in RFC 8259 mode), or unescaped ASCII control codes (0x00 through 0x1F). Objects with circular self-references are intercepted by identity tracking sets before serialization begins. Input size is bounded by browser memory (typically 50-100 MB).
Examples demonstrate an expected workflow; they do not prove every input or every branch of an external specification. Check important results with an independent source before using them for money, security, compliance, safety, or irreversible file changes.
Browser processing boundary
Tool input is processed by code running in the browser and is not intentionally sent to a CZOA processing API. The page can still request ordinary site assets, analytics, or advertising when those services are enabled. Browser extensions and managed-device software remain outside this tool's control.
Relevant references
These references govern or help explain the format, protocol, or calculation used here. Listing a reference does not claim certification or complete implementation of every optional feature.
- RFC 8259 (The JavaScript Object Notation Data Interchange Format)
- ECMA-404 (The JSON Data Interchange Standard)
Content owner: CZOA Tools · Last reviewed: 2026-09-15 · Review methodology
How to use it
- Enter, paste, or select your input data into the NDJSON / JSON Lines Formatter workspace controls.
- Review available parameter fields, units, formats, or options configured for your task.
- Click the action button or observe immediate live calculations rendered in your browser runtime.
- Inspect the resulting output and any diagnostic messages, then copy or download the result if needed.
Frequently asked questions
How does NDJSON Formatter process lines?+
It splits primary text at line endings, trims each line, discards empty lines, then strictly parses every remaining line as an independent JSON value. Each successful value is JSON-serialized with a one-based line number.
How are two NDJSON records formatted?+
`{"id":1}` and `{"id":2}` produce separate numbered entries beginning `1:` and `2:`. Each nonblank line is parsed independently; they are not combined into one array.
How are errors and blank lines handled?+
Blank or whitespace-only lines do not produce an entry. Any nonempty line that fails strict interchange JSON parsing stops the conversion rather than being silently skipped or repaired.
What NDJSON features are outside scope?+
It is a formatter, not a schema validator, stream reader, file importer, query engine, record merger, duplicate-key policy editor, or lossless source-layout preservation tool.