NestJS vs Fastify: source lines of code compared
As of 2026-08-14, nestjs/nest contains 117,116 total lines (98,271 code) across 1,798 files, while fastify/fastify contains 14,557 total lines (10,864 code) across 80 files as of 2026-08-14. nestjs/nest is about 9.0x the size of fastify/fastify by code lines. Code size is not code quality: a larger count only means more source material, not a better or worse project.
| Metric | nestjs/nest | fastify/fastify |
|---|
| Files | 1,798 | 80 |
| Total lines | 117,116 | 14,557 |
| Code lines | 98,271 | 10,864 |
| Comment lines | 9,578 | 2,127 |
| Blank lines | 9,267 | 1,566 |
| Languages counted | 11 | 5 |
Top languages in nestjs/nest: TypeScript (62.9% of code), JSON (34.8% of code), JavaScript (1.9% of code). Top languages in fastify/fastify: JavaScript (74.3% of code), TypeScript (23.5% of code), JSON (2.1% of code). TypeScript, JSON, JavaScript appear in both top language lists; GraphQL, YAML appear only in nestjs/nest's top languages; Shell, Markdown appear only in fastify/fastify's top languages.
Methodology: both counts come from cached OctoCounts reports generated with tokei. nestjs/nest was counted at ref master (commit a112f3fbd4bd) on 2026-08-14; fastify/fastify was counted at ref main (commit d693f43d890f) on 2026-08-14. See the counting methodology for ignored directories and analysis options.
Evidence and next steps:
Note: code size is not code quality. OctoCounts only reports reproducible line counts and makes no claim that either project is better.