valibot vs superstruct

validation

valibot

superstruct

Valibot and Superstruct are both JavaScript validation libraries that take a functional, composable approach to schema definition, but they serve different priorities. Valibot, released in 2023, is engineered for extreme bundle size optimization through modular, tree-shakable functions—achieving as little as 1.37 kB while maintaining strong TypeScript inference. Superstruct, a more established library from 2017-2018, offers a mature, zero-dependency functional API with rich extensibility and error handling features at 11.7 kB minified.

This comparison matters for developers choosing validation strategies in client-side applications where bundle size and performance directly impact user experience. Valibot targets teams building modern web apps where every kilobyte counts—particularly for forms, edge functions, and mobile experiences. Superstruct appeals to projects that prioritize compositional flexibility and mature error handling patterns over absolute size minimalism, especially in Node.js environments or larger applications where a few extra kilobytes are acceptable tradeoffs for established stability.

Head-to-Head

Bundle Size & Tree-Shaking→ valibot wins

valibot

Exceptionally small at 1.37 kB with aggressive tree-shaking. Each validator is an independent function, allowing bundlers to eliminate unused code. Can be up to 98% smaller than alternatives in real-world scenarios with selective imports.

superstruct

Compact at 11.7 kB minified (3.4 kB gzipped) with zero dependencies. While lightweight compared to many validators, lacks the modular function architecture that enables Valibot's extreme tree-shaking. You import the full validation core regardless of usage.

API Ergonomics & Syntax→ valibot wins

valibot

Uses functional pipes and modular checks with flat composition. Schema definitions avoid deep nesting through pipe-based transforms. Extension is straightforward—write a simple function. Syntax feels modern and composable without parentheses hell.

superstruct

Functional composition via struct nesting (e.g., pattern(size(string()))) which becomes verbose and parenthesis-heavy for complex schemas. No fluent chaining available. While composable, the nested function calls feel clunky compared to pipe-based or method-chaining alternatives.

Runtime Performancetie

valibot

Midfield validation speed—approximately twice as fast as Zod v3, similar to Zod v4. Excels in Time to Interactive (TTI) due to minimal initialization overhead. Not as fast as compiler-optimized solutions like Typia but faster than most runtime validators.

superstruct

Lightweight design suggests competitive runtime performance. Supports abort-early validation with on-demand error iteration for efficiency. Specific benchmark data limited, but mature codebase indicates stable, predictable performance without optimization bottlenecks.

TypeScript Inference Qualitytie

valibot

Strong type inference leveraging TypeScript's advanced features. Modular design produces clean inferred types without type bloat. Schema definitions translate accurately to TypeScript types with proper narrowing and refinement support.

superstruct

Excellent inference quality—types are clean and correct. Written entirely in TypeScript with careful attention to type soundness. Long-standing reputation for reliable type inference without surprises or edge cases requiring manual annotations.

Error Handling & Customization→ superstruct wins

valibot

Provides standard error objects with path information. Modular architecture makes custom validators trivial to write—just functions returning specific error formats. Growing ecosystem of community validators but less mature than established alternatives.

superstruct

Rich error handling with abort-early validation and full error iteration control. Mature patterns for custom error messages and failure refinement. Well-documented extension mechanisms for domain-specific validation logic with predictable error structures.

Ecosystem Maturity & Stability→ superstruct wins

valibot

Rapidly growing with 3,500+ GitHub stars since 2023 launch. Active development and positioning as the leading lightweight option in 2025. Younger ecosystem means fewer third-party integrations and less battle-testing in production at scale.

superstruct

Mature library maintained since 2017-2018 with stable API. Proven in production environments across diverse projects. Less active buzz than newer libraries but offers predictability and established patterns. Zero dependencies reduce maintenance burden.

Verdict

Choose Valibot if bundle size is a critical concern for your application—particularly for client-side validation in forms, edge functions, or mobile-first experiences where every kilobyte impacts load time and Time to Interactive. Its modular architecture and tree-shaking capabilities deliver unmatched size efficiency without sacrificing TypeScript quality or reasonable runtime performance. The modern pipe-based API also feels cleaner than nested function composition, making complex schemas more maintainable. Valibot is the clear choice for greenfield projects prioritizing modern DX and performance metrics.

Choose Superstruct when you need battle-tested stability, rich error handling patterns, and don't face strict bundle size constraints—typical in Node.js services, internal tools, or larger applications where 10 kB is negligible. Its mature ecosystem, zero dependencies, and established production track record provide confidence for risk-averse teams. The functional composition model, while syntactically heavier, offers powerful extensibility for complex domain validation. If your project values proven stability over cutting-edge optimization, Superstruct remains a solid, reliable choice that won't surprise you with breaking changes or immature APIs.

When to Use Each

If you are building a client-side form library with strict performance budgets → use Valibot because its 1.37 kB footprint and tree-shaking will minimize impact on initial page load while providing excellent TypeScript-powered autocomplete for form field validation.

If you are validating API request/response schemas in a Node.js backend service → use Superstruct because bundle size is irrelevant server-side, and its mature error handling with abort-early validation provides production-ready patterns for RESTful validation middleware.

If you are building an edge function on Cloudflare Workers or Vercel Edge with strict 1MB limits → use Valibot because its modular design ensures you only ship the exact validators needed, leaving maximum room for business logic within platform constraints.

If you are migrating a legacy codebase that already uses functional composition patterns → use Superstruct because its established API (since 2017) means more Stack Overflow answers, fewer breaking changes, and easier onboarding for developers familiar with functional validation paradigms.

Learn More

valibot →superstruct →

Head-to-Head

Bundle Size & Tree-Shaking→ valibot wins

valibot

superstruct

API Ergonomics & Syntax→ valibot wins

valibot

superstruct

Runtime Performancetie

valibot

superstruct

TypeScript Inference Qualitytie

valibot

superstruct

Error Handling & Customization→ superstruct wins

valibot

superstruct

Ecosystem Maturity & Stability→ superstruct wins

valibot

superstruct

Verdict

When to Use Each