SmartQueryTools

Convert NDJSON to HTML Table Online

Convert NDJSON files to an HTML table directly in your browser. Copy the markup or download a ready-to-use HTML file.

About converting NDJSON to HTML

NDJSON to HTML turns a batch of events into a table you can open in any browser. It suits quick status pages, an attachment for people without access to the logging system, or a static report built from a nightly job that writes JSON Lines. Each line becomes a <tr>, and the keys found across the file become the header cells.

Log content is untrusted input. User agents, URLs and error messages can contain angle brackets and ampersands, and some contain deliberate script injection attempts. Every value is HTML-escaped, so <script> in a logged request path is displayed as text rather than executed. That makes the output safe to open, even when it comes from security or access logs.

The table has no styling, and long values such as stack traces are not wrapped or truncated for you. Multi-line messages keep their line breaks in the source, but the browser renders them as spaces unless you add white-space: pre-wrap to the cells. Only the first 1,000 lines are included, and nested objects appear as escaped JSON text. For longer incidents, publish a filtered table and link to the full log instead.

Worked example

A small sample file, converted with the default settings.

Input (NDJSON)

{"ts":"2026-03-02T14:05:11.042Z","level":"info","service":"checkout","status":200,"latency_ms":41.7,"user_id":"u_1842"}
{"ts":"2026-03-02T14:05:12.310Z","level":"error","service":"checkout","status":502,"latency_ms":3012.4,"user_id":null}
{"ts":"2026-03-02T14:05:12.877Z","level":"info","service":"search","status":200,"latency_ms":12.9,"user_id":"u_0077"}
{"ts":"2026-03-02T14:05:14.105Z","level":"warn","service":"search","status":429,"latency_ms":0.8,"user_id":"u_1842"}

Output (HTML)

<table>
<thead>
  <tr><th>ts</th><th>level</th><th>service</th><th>status</th><th>latency_ms</th><th>user_id</th></tr>
</thead>
<tbody>
  <tr><td>2026-03-02T14:05:11.042Z</td><td>info</td><td>checkout</td><td>200</td><td>41.7</td><td>u_1842</td></tr>
  <tr><td>2026-03-02T14:05:12.310Z</td><td>error</td><td>checkout</td><td>502</td><td>3012.4</td><td></td></tr>
  <tr><td>2026-03-02T14:05:12.877Z</td><td>info</td><td>search</td><td>200</td><td>12.9</td><td>u_0077</td></tr>
  <tr><td>2026-03-02T14:05:14.105Z</td><td>warn</td><td>search</td><td>429</td><td>0.8</td><td>u_1842</td></tr>
</tbody>
</table>

What changes when you convert NDJSON to HTML

  • <thead> holds one <th> per key: ts, level, service, status, latency_ms and user_id.
  • Each log line becomes a <tr> inside <tbody>, in file order.
  • The null user_id on the error line is an empty <td></td>.
  • The characters &, <, > and double quotes inside values are escaped as entities.
  • No CSS, <html> or <head> is added; the output is a table fragment.

Your file is processed locally in your browser and is never uploaded. The free limit is 50 MB per file; larger files work if your device has the memory for them.

Frequently Asked Questions

Is it safe to render logs that contain HTML or scripts?

Yes. Values are escaped before they are placed in cells, so tags in the log appear as literal text. Nothing from the data is interpreted as markup.

How do I highlight error rows?

The rows have no classes, so style them after converting. The simplest route is to filter the NDJSON to errors and produce a separate table, or add a few lines of JavaScript that colour rows whose level cell reads error.

Why do stack traces appear on one line in the browser?

HTML collapses line breaks in normal text. Add td { white-space: pre-wrap; } to a <style> block or your stylesheet and the original breaks will show.

What is HTML format?

HTML (HyperText Markup Language) is the markup language of the web. An HTML table can be pasted directly into a web page or opened in a browser — no CSS or JavaScript required.

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