OSS TanbouOn this page
Overview
ts-toolbelt is a TypeScript utility library with more than 200 mapped, conditional, and recursive type helpers. Its Object, List, Union, Function, and other categories provide reusable building blocks for merges, optional fields, paths, and other advanced type computations.
Features and best fit
Based on official documentation; not hands-on tested · Content checked:
Key features
Choose utilities by Object, List, Union, Function, and other categories
The README advertises more than 200 utilities organized around TypeScript concepts such as Object, List, Union, Function, String, and Number, making advanced operations discoverable by category.
Sources: [2]
Compose Merge, Optional, path, and other advanced type operations
Utilities such as Object Merge and Optional, path-oriented helpers, and Union or Function utilities reduce the need to rebuild complex mapped and conditional types in each project.
Sources: [2]
Choose explicit, compact, or portable import styles
The README documents explicit names such as Object, compact aliases such as O, and a default portable import, letting projects match their existing type-import style.
Sources: [2]
Best fit
Fits TypeScript frontends and libraries with repeated complex generic types
It is useful when nested object transformations, union manipulation, or function-signature types recur across modules and the type-level implementation should be centralized.
Sources: [2]
Before adoption
The documented prerequisite still targets TypeScript ^4.1.0
The README lists TypeScript ^4.1.0 as a prerequisite and strongly recommends strictNullChecks: true. Projects on newer compilers should run their own typecheck against the target TypeScript version before broad adoption.
Sources: [2]
Check package 9.6.0 against the compiler version used by the project
Repository package metadata reports version 9.6.0, while the GitHub repository was last pushed in June 2025. Validate the specific utilities you need with the project's compiler before making them a widely shared dependency.
Official sources
- [1]millsp/ts-toolbelt repository metadata(2026-10-05)
- [2]ts-toolbelt README at reviewed commit(2026-10-05)
- [3]ts-toolbelt package metadata at reviewed commit(2026-10-05)
- [4]ts-toolbelt Apache-2.0 license(2026-10-05)
Supplemental curator note
The README still documents TypeScript ^4.1.0 as its prerequisite, and the repository was last pushed in June 2025. On newer compilers, type-check the utilities you need against the target TypeScript version before making this a shared dependency.
Try it in 3 steps
- 1
Install ts-toolbelt 9.6.0 with a TypeScript version in the documented range
Create an isolated project with ts-toolbelt 9.6.0 and a compiler inside the README's TypeScript ^4.1.0 prerequisite.
demo=$(mktemp -d "${TMPDIR:-/tmp}/ts-toolbelt.XXXXXX") && cd "$demo" && npm init -y >/dev/null && npm install --save-exact ts-toolbelt@9.6.0 && npm install --save-exact --save-dev typescript@4.9.5 - 2
Enable strict checking and use Object.Merge
Enable strictNullChecks as strongly recommended by the README and exercise the representative Object.Merge utility.
printf "%s\n" '{"compilerOptions":{"strict":true,"strictNullChecks":true,"noEmit":true,"lib":["ES2015"]}}' > tsconfig.json && printf "%s\n" "import {O} from 'ts-toolbelt';" "type User = O.Merge<{name: string}, {age?: number}>;" "const user: User = {name: 'Ada'};" "void user;" > index.ts - 3
Type-check the project
Run the compiler in the documented range and confirm that ts-toolbelt's type utilities resolve correctly.
npx tsc
Growth
Growth trends · Last 30 days
7,150 Stars
Trend data is still being collected.
Development activity
Last 90 days · weekly
- Commits (last 30 days)
- 0
- Open PRs
- 17
Development activity is still being collected.
Built with
Categories and tags
Categories
GitHub data
GitHub dataView detailed GitHub data
GitHub Topics
- typescript
- types
- typescript-library
- type-checking
- dynamic-types
- type-utilities
- type-safety
- utility
- safety
- Stars
- 7,150
- Forks
- 152
- Watchers
- 29
- Open issues
- 66
- Contributors
- 14
- Owner type
- User
- Primary language
- TypeScript
- License
- Apache-2.0
- Repository last updated
- Jun 2, 2025
Related information
Write a related articleShare a guide or use case for this OSS in Markdown. Articles are published after administrator approval.
Explore next
- Yup23,660 Stars
3 shared tag(s) · 1 shared category(s) · Same language
transform and validate runtime values from schemas while inferring TypeScript types
TypeScript - Type-fest17,433 Stars
3 shared tag(s) · 1 shared category(s) · Same language
reuse TypeScript type transformations that go beyond the built-in utility types
TypeScript - typescript-eslint16,408 Stars
3 shared tag(s) · 1 shared category(s) · Same language
bring ESLint recommended rules and TypeScript parsing together in a Flat Config setup
TypeScript - Faker15,509 Stars
3 shared tag(s) · 1 shared category(s) · Same language
generate realistic-looking people, locations, products, and other fake data for testing and development
TypeScript - Linaria12,350 Stars
3 shared tag(s) · 1 shared category(s) · Same language
keep CSS-in-JS authoring while extracting styles to static CSS at build time
TypeScript - Valibot9,027 Stars
3 shared tag(s) · 1 shared category(s) · Same language
combine small functions for runtime schema validation with TypeScript type inference
TypeScript
Report incorrect information
Tell us if any listing information is incorrect or outdated.