Performance
Fallow is a compiled Rust binary with rayon-based parallelism. Knip runs on Node.js. Version 6 adopted the Oxc parser via NAPI bindings, which significantly narrowed the gap with v5, but knip remains single-threaded. Cold runs (no cache) so both tools work from scratch. Fastest tool per row in bold.Benchmarked on real-world open-source projects from 174 to 38,146 files against fallow 2.100.0, knip 5.87.0, and knip 6.6.1 on Apple M5 (10 cores), 32 GB RAM, macOS 26.4, Node v22.22.1. Median of 5 cold runs (no cache) with 2 warmups. The knip v6 column is the primary comparison; current knip v5 and v6 produce equivalent timings on the projects they can load, and fallow’s lead over knip v5 is wider on the small-to-mid projects (for example fallow 13.7x on fastify, 13.0x on zod, 10.3x on preact). fallow is fastest on small-to-mid projects (fastify, preact, query, svelte, zod). On large projects, knip v6’s Oxc parser is faster on astro and TypeScript; fallow’s advantage there is doing more in one tool. fallow’s persistent cache makes repeat (warm) runs faster again, the table uses the conservative cold numbers.¹ Current knip (both v5 and v6) exits without valid output on next.js, vite, and vue/core. It loads and executes a project’s own config and JSON files to read plugin settings, which works well on apps but trips on a few framework monorepos where fallow (purely syntactic, no config execution) completes with no setup. vite: a workspace
package.json carries a UTF-8 BOM that knip’s JSON.parse rejects (a robustness gap, reportable upstream; fallow strips BOMs). vue/core: a private sfc-playground/vite.config.ts fails to load. next.js: the framework’s own monorepo needs a build for its jest config and per-workspace entry config for its dist-published packages, this is the framework source, not a Next.js app (which is what knip’s Next.js plugin targets). All are fixable with knip config; fallow needs none.Why fallow is faster
Memory and large codebases
Fallow uses flat edge storage and lock-free parallel resolution, so it handles large monorepos well. Memory usage scales linearly with file count rather than with the Node.js GC heap.Detection capabilities
- Comparison table
- Details
Plugin coverage
Knip has broader plugin coverage, particularly for niche and legacy tooling. Fallow covers all major frameworks and the most popular tools across every category.
- Fallow-only plugins
- Knip-only plugins
If your project uses a framework that fallow doesn’t have a plugin for, you can create a custom plugin in JSONC, JSON, or TOML. No code required.
Features fallow has that knip doesn’t
SARIF output
Upload results directly to GitHub Code Scanning with
--format sarif. Integrated into your PR review workflow.Baseline comparison
--save-baseline and --baseline for incremental CI adoption. Only fail on new issues, not pre-existing ones.Inline suppression
// fallow-ignore-next-line and // fallow-ignore-file comments for granular, per-line suppression without config changes.Code duplication
Built-in
fallow dupes with four detection modes, clone family grouping, cross-language matching, and refactoring suggestions.Complexity and health score
fallow health reports cyclomatic / cognitive complexity, CRAP score, risk profiles, and a composite health score. --max-crap, --max-cyclomatic, and --max-cognitive gate CI on per-function thresholds.Architecture boundaries
Enforce cross-package or cross-layer import rules. Boundary violations fail the build without needing ESLint plugins.
Feature flag detection
fallow flags detects feature flag patterns across the codebase, cross-references them with dead code, and exports to SARIF, markdown, and MCP.Combined audit
fallow audit runs dead code, health, and duplication with a single verdict. Per-analysis baselines (--dead-code-baseline, --health-baseline, --dupes-baseline) let each slice use its own reference.Standalone rule explainer
fallow explain <issue-type> prints rule rationale, a worked example, fix guidance, and the docs URL without running analysis. Knip has no equivalent. Closest analogs are Credo (mix credo explain) for Elixir and Biome’s build-time diagnostic explainer; only fallow ships a standalone CLI subcommand plus an MCP tool (fallow_explain) that agents can call before fixing a finding.Git-aware analysis
--changed-since <ref> for file-level scoping and --changed-workspaces <ref> for monorepo-level scoping. Perfect for PR-only CI checks.Workspace filtering
--workspace accepts comma-separated values, globs, and ! negations (-w 'apps/*' -w '!apps/legacy'). Works across every command.Output grouping
--group-by owner|directory|package|section partitions findings. owner and section read GitHub / GitLab CODEOWNERS so unused code is routed to the right reviewer.Auto-fix dry run
Preview all fixes with
fallow fix --dry-run before applying. JSON output for programmatic review.Trace and debug tooling
--trace FILE:EXPORT to trace export usage chains, --trace-file PATH for file edges, --trace-dependency PACKAGE for dependency usage, --performance for pipeline timing.CSS Modules tracking
.module.css and .module.scss class names are extracted as named exports and tracked through styles.className member accesses.MCP server
Built-in
fallow-mcp exposes analyze, find_dupes, check_health, audit, check_runtime_coverage, and more as typed tools for AI agents.Claude Code hooks
fallow hooks install --target agent installs a PreToolUse gate that blocks git commit / git push when fallow audit fails, with a structured envelope agents can act on.- Class member detection: Knip dropped this in v6; fallow retains it with decorator-aware skip logic for NestJS, Angular, TypeORM, etc.
- Production mode:
--productionexcludes test/dev files and detects type-only dependencies that should be devDependencies. - Duplicate export detection: Finds the same symbol exported from multiple modules.
- TOML configuration: In addition to JSONC/JSON, fallow supports
fallow.tomlfor teams that prefer TOML. - Cross-reference analysis:
check --include-dupesfinds dead code that is also duplicated, showing high-priority cleanup targets. - Runtime coverage intelligence (paid): V8 runtime evidence merged with static analysis via a signed sidecar. Adds hot/cold paths, runtime-weighted health scoring, and stale-flag evidence.
Features knip has that fallow doesn’t
More plugins
Knip covers more niche, legacy, and ecosystem-specific tooling.
Custom reporters
Write custom reporter functions in JavaScript for fully custom output formatting.
Tags filtering
--tags flag filters results based on JSDoc @public/@internal annotations.- TS namespace declaration member detection: New in v6, detects unused members in TypeScript
namespacedeclarations (notimport * as ns, fallow already handles that via namespace import narrowing).
When to choose fallow
Speed matters
Large codebases where sub-second analysis enables watch mode and tight CI feedback loops.
CI pipelines
SARIF for GitHub Code Scanning, baselines for incremental adoption,
--changed-since for PR-scoped checks.Dead code + duplication
Replace both knip and jscpd with a single tool. Cross-reference dead code with duplication for prioritized cleanup.
Gradual adoption
Per-issue severity rules (
error/warn/off) and inline suppression comments let teams adopt incrementally.AI-assisted development
Your team uses AI coding agents. Fallow provides
--format json for CLI, an MCP server for typed tool calling, and --changed-since for PR-scoped checks.When to choose knip
Niche plugins
Your project depends on a specific tool that only knip has a plugin for, and a custom plugin isn’t worth the effort.
Already working well
Knip is already integrated and performance isn’t a pain point. No reason to migrate for the sake of it.
Custom reporters
You need fully custom output formatting via JavaScript reporter functions.
Summary table
Migrating from knip?
If you’re coming from knip, fallow has a one-command migration path that automatically translates your configuration.Migrate from knip
Automatic config migration with
fallow migrate.Quick Start
Get started with fallow in 2 minutes.