Effect-TS vs fp-ts vs neverthrow (2026)

TypeScript's try/catch loses type information about errors. These three libraries bring type-safe error handling to TypeScript.

Quick Comparison

Feature	Effect-TS	fp-ts	neverthrow
Approach	Full framework	FP library	Result type only
Learning Curve	Steep	Steep	Easy
Bundle Size	Large	Medium	Tiny (~2KB)
Error Types	✅ Typed	✅ Typed	✅ Typed
Async	✅ Built-in	⚠️ TaskEither	✅ ResultAsync
Concurrency	✅ Fibers	❌	❌
Dependencies	✅ Services	❌	❌
Ecosystem	Growing fast	Mature	Minimal

neverthrow — The Simple Choice

import { ok, err, Result } from 'neverthrow'

function divide(a: number, b: number): Result<number, string> {
  if (b === 0) return err('Division by zero')
  return ok(a / b)
}

const result = divide(10, 2)

result.match(
  (value) => console.log(`Result: ${value}`),
  (error) => console.log(`Error: ${error}`),
)

// Or chain operations
divide(10, 2)
  .map(n => n * 2)
  .mapErr(e => `Failed: ${e}`)

Pros: Tiny, easy to learn, drop into any project. Cons: Just a Result type — no async handling, no dependency injection.

fp-ts — The FP Library

import { pipe } from 'fp-ts/function'
import * as E from 'fp-ts/Either'
import * as TE from 'fp-ts/TaskEither'

const divide = (a: number, b: number): E.Either<string, number> =>
  b === 0 ? E.left('Division by zero') : E.right(a / b)

pipe(
  divide(10, 2),
  E.map(n => n * 2),
  E.fold(
    (error) => console.log(`Error: ${error}`),
    (value) => console.log(`Result: ${value}`),
  ),
)

Pros: Comprehensive FP toolkit, mature, well-documented. Cons: Verbose, steep learning curve, pipe everywhere, losing momentum to Effect.

Effect-TS — The Full Framework

import { Effect, pipe } from 'effect'

const divide = (a: number, b: number) =>
  b === 0
    ? Effect.fail(new Error('Division by zero'))
    : Effect.succeed(a / b)

const program = pipe(
  divide(10, 2),
  Effect.map(n => n * 2),
  Effect.tap(n => Effect.log(`Result: ${n}`)),
)

Effect.runPromise(program)

Pros: Type-safe errors, concurrency, dependency injection, retries, scheduling — it's a full framework for building reliable software. Cons: Massive learning curve, large bundle, opinionated, changes how you write TypeScript.

Decision Guide

Situation	Choose
Add Result type to existing project	neverthrow
Learning functional programming	fp-ts
Building a complex, reliable system	Effect-TS
Small team, quick project	neverthrow
Want typed errors only	neverthrow
Want everything (DI, concurrency, retries)	Effect-TS

FAQ

Is Effect-TS worth the complexity?

For large applications with complex error handling, dependency injection, and concurrency needs — yes. For simple CRUD apps — overkill.

Is fp-ts dead?

Not dead, but losing momentum to Effect-TS. Effect provides a more pragmatic approach to the same problems.

Can I use neverthrow with React?

Yes. It's just a data structure. Use in server actions, API routes, or any TypeScript code.

Bottom Line

neverthrow for simple typed errors (80% of projects need only this). Effect-TS for complex systems requiring full reliability guarantees. fp-ts if you want classic Haskell-style FP. Start with neverthrow — upgrade to Effect when complexity demands it.