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Microsoft

TypeScript — Engineering Performance

10 engineers all time · Jan 2025 – Aug 2026 · built 2026-08-23 · GitHub

Performance snapshot

Today's rolling 90-day reading for TypeScript, compared with the start of the series. Pick a window to move that comparison point.

Eff. capacity added

+24.0engineers

5 devs deliver like 29 (5.8x pre-AI)

Avg. perf / dev / mo (ETV)

+145.9%

2.03 → 4.98

Active engineers

−28.6%

7.0 → 5.0

Features

+19.4pp

25.7% → 45.1%

TypeScript vs. Microsoft

Per-engineer ETV for TypeScript against Microsoft as a whole. Both lines are 90-day rolling averages scaled to a 30-day month, so they share one axis and can be read against each other at any point. Pick a window to zoom the chart to it.

TypeScript
4.98ETV / dev / mo
−0.91 (−15.4%) past 90d
Microsoft
4.52ETV / dev / mo
+1.48 (+48.7%) past 90d

Performance over time

ETV stacked by Features / Maintenance / Tests / Docs / Fixes — 90-day moving average, normalized to ETV / month.

Engineering capacity

Effective engineers behind TypeScript, in pre-AI terms. Per-engineer ETV divided by the Q1 2025 baseline of 0.86 ETV / dev / mo gives a capacity multiple, and that multiple applied to the engineers active in the trailing 90 days turns it into engineer-equivalents. The line is the real headcount, so the gap between line and area is what the leverage is worth.

Effective engineers
29engineer-equivalents
+24 engineers above real headcount
Real engineers
5engineers
active in the trailing 90 days
Capacity vs pre-AI
5.8x
per engineer, vs 0.86 ETV / dev / mo

Knowledge concentration

How dependent is this repo on a small number of engineers? Higher top-1 share = higher key-person risk.

Top 1
57.4 %
Top 3
90.4 %
Top 5
97.8 %

Jake Bailey owns 57.4 % of commits.

Reports

Written summary of the work completed each month.

No monthly reports available yet.

Top engineers

Most impactful commits

Top 10 by ETV in the all-time window.