Apex Log Parser

Fast Apex log parser for Salesforce debug logs: a typed call tree with timings, governor limits and SOQL/DML counts. TypeScript, Node.js and browser. No dependencies.

The parser behind the Apex Log Analyzer for VS Code.

Features

• Fast. A 20 MB log parses in 33 ms and holds 11 MB; 100 MB in 131 ms and 37 MB.
• Any source. A string, bytes, Blob, fetch Response, ReadableStream or async iterable.
• Off the main thread. Parses in 5 ms slices with signal and onProgress, or in a worker (@apexdevtools/apex-log-parser/worker).
• Every documented event type, matched to its exit, with self and total times in nanoseconds.
• Counts up the tree: SOQL, DML and SOSL statements and rows, exceptions and heap.
• Governor limits per namespace, with a snapshot for each limit block.
• Variables that each event of a FINEST log could see.
• Column arrays (log.columns) for fast repeated passes, as a flame chart or call tree.

Performance

Parse:

Log size	v0.2	v0.3	v0.4
8 MB	106 ms, 104 MB	86 ms, 77 MB	15 ms, 4 MB
20 MB	274 ms, 259 MB	221 ms, 190 MB	33 ms, 11 MB
50 MB	550 ms, 555 MB	426 ms, 408 MB	66 ms, 19 MB
100 MB	1,116 ms, 1,105 MB	829 ms, 812 MB	131 ms, 37 MB

Synthetic logs, median of 5 runs, M4 Pro, Node.js 24. The log is in memory before the timer starts: bytes for v0.4, a string for v0.2 and v0.3. Memory is what the parsed log holds, without the log itself.

Read, after the parse: a 95 MB real log, 432,000 events, first read / repeat read:

Work	Event objects	log.columns
Numbers only: depth, self time, SOQL count	11 / 10 ms	9 / 4 ms
Flame chart: tree walk, a label per frame	108 / 26 ms	87 / 16 ms
Call tree: self time per method	117 / 36 ms	83 / 5 ms

The parse holds 25 MB. Reads add 0–2 MB through event objects, 3–6 MB through columns (26 MB for every column). v0.3 held 761 MB.

Usage

npm install @apexdevtools/apex-log-parser

import { parse } from '@apexdevtools/apex-log-parser';

const log = await parse(logText);

// null when the log's debug levels did not record these lines.
console.log(`${log.soqlCount?.total} queries, ${log.dmlRowCount?.total} DML rows`);
console.log(`CPU: ${log.limits.final.cpuTime.used} ms`);

const slowest = [...log.ofType('METHOD_ENTRY')].sort((a, b) => b.duration.self - a.duration.self);
for (const method of slowest.slice(0, 10)) console.log(method.text, method.duration.self);

The type declarations document every field. Upgrading from v0.3 or earlier: see the CHANGELOG.

Requirements

Node.js 22+ (the worker option needs 22.3+), modern browsers, Deno or Bun. ESM only.

License

BSD-3-Clause - Certinia Inc.