Code · nhsengland · UK Public Sector GitHub Observatory

Language figures come from GitHub's own per-repository byte counts, which measure source rather than a single headline label. File counts and repository sizes come from the mirrors themselves. The two tell different stories, and the difference is the point.

The codebase

languages in use

95.2 MB of source

17.6k

files at HEAD

across every analysed repository

0 B

on disk as mirrors

full history, every branch and tag

323.1 MB

largest repository

swpc_synthea

What stands out

One archived repository holds 17% of all the bytes.

swpc_synthea is 323.1 MB of git - a 2013 static snapshot of www.gov.uk, not source code. It single-handedly makes HTML the largest language by volume (43% of all source bytes). Any size or language statistic that does not exclude it is measuring an archive, not a codebase.

Sizes here are GitHub's reported figures.

This organisation was harvested with blobless partial clones, which fetch every commit and file path but not file contents, so there is no local size to measure against. Checked elsewhere in this dataset against 1,526 fully mirrored repositories, GitHub's reported size is accurate to within about six percent.

Ruby is the house language, but its share is falling.

Ruby is the primary language of 0% of archived repositories but only 0% of live ones. Python, Go, TypeScript and HCL have taken the difference - the signature of a shift from monolithic Rails publishing apps toward data pipelines, infrastructure-as-code and platform tooling.

Most repositories are small; a handful are enormous.

65% of repositories are under a megabyte of git data. The estate is not a monolith - it is a very long tail of small services, gems and prototypes around a few large publishing applications.

Languages, two ways

By volume of source

Bytes of code. Dominated by archived static HTML.

By number of repositories

How many repositories name each language as their primary one. A better guide to what engineers actually work in.

Live estate versus archive

The same language ranking, split by whether the repository is still active. The shift is the clearest signal of technical direction in the whole dataset.

Active repositories

Archived repositories

Scale

Repository size distribution

Git data per repository, log-ish buckets.

Commits against files

Each circle is a repository, sized by number of distinct authors. Both axes are logarithmic. The diagonal band is the normal relationship between codebase size and churn; outliers above it are long-lived apps with heavy iteration, below it are dumps and imports.

The shape of a repository

Directory layout is the cheapest reliable signal of what a repository actually is. app/ with config/ and spec/ is a Rails application; src/ with test/ is Java or Node. Counted by how many repositories contain each top-level directory at HEAD.

Most common top-level directories

Most common file extensions

By total file count across the estate.

The twenty largest repositories

Repository	Language	Git size	Commits	Files	Status
swpc_synthea	Java	323.1 MB	4,944	552	active
AIF_Allocation_Tool_update	Python	111.0 MB	187	13	archived
data-hazards-nhse	-	109.3 MB	449	46	active
AIF_Allocation_Tool	Python	100.7 MB	189	12	active
datascience	HTML	100.5 MB	1,140	335	active
causal-handbook	TeX	91.2 MB	42	153	active
opensource_maternity_dashboard_project	Python	83.5 MB	97	19	active
ProcessMining	Jupyter Notebook	74.3 MB	19	36	active
datascience-pd-newsletter	-	59.6 MB	423	110	active
mm-healthfair	Python	51.5 MB	507	316	active
git-and-github-cicd-workshop	Python	41.6 MB	82	55	active
analytical-data-style-guide-SW	HTML	40.4 MB	423	84	active
futurenhs	C#	40.1 MB	2,721	1,903	active
package-your-code-workshop	Python	39.7 MB	61	48	active
data-viz-community-of-practice	HTML	36.7 MB	246	169	active
AmbModelOpen	R	29.9 MB	43	204	active
ds_251_RAG	Jupyter Notebook	29.4 MB	86	36	active
nhs-r-reporting	R	29.4 MB	264	498	active
NHSSynth	Jupyter Notebook	27.7 MB	642	143	active
NEY-Inequalities-Methodologies	HTML	26.1 MB	26	31	active