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ofetch makes it easy to add custom headers to your requests using the headers option.
Basic Usage Object notation
Headers instance
Array notation
import { ofetch } from 'ofetch' await ofetch ( '/api/users' , { headers: { 'Authorization' : 'Bearer token123' , 'X-Custom-Header' : 'value' } })
When sending JSON bodies, ofetch automatically sets headers for you:
await ofetch ( '/api/users' , { method: 'POST' , body: { name: 'John' } }) // Automatically adds: // content-type: application/json // accept: application/json
You can override these defaults:
await ofetch ( '/api/users' , { method: 'POST' , body: { name: 'John' }, headers: { 'content-type' : 'application/vnd.api+json' } })
Headers are merged when using $fetch.create() or when passing a Request object:
const api = ofetch . create ({ headers: { 'Authorization' : 'Bearer token123' , 'X-API-Version' : '1.0' } }) // These headers are merged with the defaults await api ( '/users' , { headers: { 'X-Custom-Header' : 'value' , 'X-API-Version' : '2.0' // Overrides default } }) // Final headers: // Authorization: Bearer token123 // X-API-Version: 2.0 // X-Custom-Header: value
Headers from Request objects are preserved and can be overridden:
const req = new Request ( 'https://api.example.com/users' , { headers: { 'foo' : '1' } }) await ofetch ( req , { headers: { 'foo' : '2' , // Overrides Request header 'bar' : '3' // Added to Request headers } }) // Final headers: foo: 2, bar: 3
Common Patterns Authentication const api = ofetch . create ({ baseURL: 'https://api.example.com' , headers: { 'Authorization' : `Bearer ${ getToken () } ` } })
API Versioning await ofetch ( '/api/users' , { headers: { 'Accept' : 'application/vnd.myapi.v2+json' } })
Custom User Agent await ofetch ( 'https://api.example.com/data' , { headers: { 'User-Agent' : 'MyApp/1.0' } })
Content Negotiation await ofetch ( '/api/report' , { headers: { 'Accept' : 'application/pdf' }, responseType: 'blob' })
Type Definition Headers inherit from the standard RequestInit interface and support all native header formats:
Where HeadersInit can be:
Headers instanceRecord<string, string>[string, string][]
Implementation Details Headers are internally converted to a Headers instance and merged using the mergeHeaders function from src/utils.ts:121-138. Default headers are set at src/fetch.ts:144-153 for JSON-serializable bodies.