Functional Utilities & Type Helpers

The post-Lodash era of TS utilities. The defaults are smaller, tree-shakeable, type-aware.

General utility libraries (Lodash replacements)

• ★ Remeda — TypeScript-first, fully typed, dual-API (data-first and pipe). The default new-project utility lib.
• just-* — tons of single-function packages; pick what you need.
• es-toolkit — modern alternative; very small, very fast.
• Lodash — still huge install base; tree-shakeable via lodash-es. Less recommended for new TS projects.
• rambda / Ramda — functional / curried; smaller than Ramda; rambda is the actively maintained fork.

Pattern matching

• ★ ts-pattern — exhaustive pattern matching with TypeScript narrowing. The default for replacing nested ifs / switches.
• @arktype/util — primitive helpers from ArkType.
• TC39 Pattern Matching proposal — still in flight.

Result types / no-throw error handling

• ★ neverthrow — Result<T, E> types; no thrown errors, exhaustive handling. The default for new projects.
• Effect — full ecosystem (see below); has Either / Effect for the same problem.
• oxide.ts — Rust-style Result and Option.

Type helpers

• ★ type-fest — pick / omit / partial-deep / require-at-least-one — the canonical library of useful type helpers.
• ts-toolbelt — older, larger; more obscure types.
• hotscript — type-level functional programming; advanced.

Effects / structured concurrency

• ★ Effect-TS — typed effects, structured concurrency, schema, retry, fibers, dependency injection. A complete way of writing TS that's very different from idiomatic Node — but unbelievably powerful for complex apps. Big ecosystem (@effect/schema, @effect/platform, @effect/ai, etc.) in 2026.
• fp-ts — older functional library; effectively merged into Effect.
• rxjs — reactive streams; mature, niche.

Async helpers

• p-queue, p-throttle, p-limit, p-retry, p-map — Sindre Sorhus's p-* family. Boring and bulletproof.
• TanStack Pacer — rate-limiting / debouncing primitives that integrate with TanStack Query.
• @tanstack/react-virtual — for virtualization.
• Promise.withResolvers() — built-in (TC39).

Useful small libs

• dequal — fast deep equality.
• fast-deep-equal — alternative.
• proxy-memoize — for memoizing selectors with structural equality.
• klona — fast deep clone.
• immer — immutable-by-mutation; pairs with Zustand / Redux Toolkit.
• mitt — tiny event emitter.
• ofetch — see HTTP Clients.

Pick this if…

• Default Lodash replacement: Remeda.
• Pattern matching: ts-pattern.
• Result types over throwing: neverthrow.
• Type helpers: type-fest.
• Going all-in on a structured concurrency / effects model: Effect-TS.
• Async rate limit / queue: the p-* family.