axios vs ky

data-fetching

axios

Axios and Ky are both promise-based HTTP clients for JavaScript, but they take fundamentally different approaches. Axios is a mature, feature-rich library built on XMLHttpRequest with extensive browser support and a large ecosystem. Ky is a modern, lightweight alternative that wraps the native Fetch API with quality-of-life improvements like automatic retries, better error handling, and a smaller footprint.

This comparison matters because choosing the wrong HTTP client can impact bundle size, development velocity, and browser compatibility. Axios targets teams needing comprehensive features and legacy browser support, while Ky appeals to developers building modern applications who prioritize simplicity and performance. Understanding their trade-offs helps you select the right tool for your specific constraints.

Head-to-Head

Bundle Size→ ky wins

axios

Significantly heavier footprint due to comprehensive feature set and XMLHttpRequest implementation. The extra weight comes from backward compatibility layers and built-in features that may go unused in simpler applications.

Approximately 157KB total size, making it one of the lightest full-featured HTTP clients available. The minimal footprint comes from leveraging native Fetch API rather than reimplementing HTTP logic, ideal for performance budgets.

API Ergonomicstie

axios

More opinionated API with dedicated methods for common patterns. Uses `data` for request bodies instead of `body`, includes built-in `transformRequest` and `transformResponse` helpers, and provides a consistent interface across request methods. Requires learning Axios-specific conventions.

Mirrors Fetch's minimalist philosophy while adding convenience methods like `.json()` chaining. The API feels familiar to anyone who knows Fetch, with less abstraction. Automatic JSON parsing eliminates boilerplate but offers fewer built-in transformation utilities.

Retry Logic→ ky wins

axios

No built-in retry mechanism. Developers must implement retry logic manually or use third-party plugins like axios-retry. This adds configuration complexity but provides full control over retry behavior and conditions.

Built-in retry support with exponential backoff out of the box. Configurable retry count and conditions without additional dependencies. The default behavior handles transient network failures intelligently, reducing boilerplate for common scenarios.

Browser Compatibility→ axios wins

axios

Supports IE11 and older browsers through XMLHttpRequest. Works universally across all environments without polyfills. This broad compatibility makes it the default choice for enterprise applications with diverse user bases.

Requires modern browsers (Chrome 42+, Firefox 39+, Safari 10.1+) since it depends on native Fetch. No IE11 support without polyfills. For Node.js, requires separate ky-universal package wrapping node-fetch until Node v18+ with native fetch.

TypeScript Integration→ ky wins

axios

Strong type definitions maintained separately from core library. Generic types available for request/response typing, but type inference for JSON parsing requires manual annotation. Mature typings cover the entire API surface comprehensively.

Built with TypeScript from the ground up, providing superior type inference. The `.json()` method returns properly typed responses rather than `any`. Generic types flow naturally through the call chain, reducing the need for explicit type annotations.

Interceptor Architecture→ axios wins

axios

Powerful request/response interceptor system allowing multiple interceptors to be chained. Interceptors can transform data, modify headers, handle errors globally, and even retry requests. Essential for complex authentication flows and centralized error handling in large applications.

Uses hooks pattern (beforeRequest, afterResponse) instead of interceptors. Less complex but also less powerful for advanced transformation pipelines. Adequate for most use cases but may require workarounds for sophisticated middleware patterns.

Verdict

For new projects targeting modern browsers, choose Ky. Its smaller bundle size, built-in retry logic, and superior TypeScript integration make it the better default for most contemporary web applications. The Fetch-based API means you're learning standard web APIs rather than library-specific abstractions, and the quality-of-life improvements like automatic JSON handling and exponential backoff reduce boilerplate without adding bloat. If you're working in Node.js v18+ or building browser-only applications, Ky provides the best developer experience with minimal overhead.

Choose Axios when you need IE11 support, require sophisticated interceptor chains for complex authentication or request transformation logic, or are working within an existing codebase that already uses Axios extensively. The mature ecosystem and extensive community support make troubleshooting easier, and its opinionated API can accelerate development in teams familiar with its conventions. For enterprise applications with diverse browser requirements or projects needing advanced middleware patterns, Axios remains the pragmatic choice despite its larger footprint.

When to Use Each

If you are building a modern SPA with aggressive performance budgets → use Ky because its 157KB footprint and tree-shakeable design minimize impact on load times while providing all essential features like retries and timeouts.

If you are maintaining an enterprise application requiring IE11 support → use Axios because it's the only option with native XMLHttpRequest support, avoiding polyfill complexity and ensuring consistent behavior across legacy browsers.

If you are developing a TypeScript-first application with complex API responses → use Ky because its native TypeScript implementation provides superior type inference for JSON responses, reducing manual type assertions throughout your codebase.

If you are building a microservices client with complex authentication flows and request transformations → use Axios because its powerful interceptor system elegantly handles token refresh, request signing, and centralized error handling that would require custom abstractions in Ky.

Learn More

axios →ky →

Head-to-Head

Bundle Size→ ky wins

axios

API Ergonomicstie

axios

Retry Logic→ ky wins

axios

Browser Compatibility→ axios wins

axios

TypeScript Integration→ ky wins

axios

Interceptor Architecture→ axios wins

axios

Verdict

When to Use Each