Updates the document only if the client's ETag is current

PUThttps://api.testingapis.com/api/cache/etagSign in to see this endpoint's URL

Requires If-Match with the current ETag (strong comparison, so W/ tags never match; * matches). A successful update increments the version and returns the new ETag. Use it to test lost-update protection.

Note: Send the current ETag (from GET /api/cache/etag) in If-Match. Missing -> 428, stale -> 412.Note: Send the current ETag (from GET …) in If-Match. Missing -> 428, stale -> 412.

Parameters 1

Name	Type	Description
`If-Match`	header · string	Current ETag. Missing returns 428, stale returns 412.

Request body

Optional. application/json, text/json, application/*+json, application/xml, text/xml, application/*+xml. Model: CachingControllerDocumentUpdate. New title and/or content.

Example body

{"title": "Updated title", "content": "New content"}

Responses

200: Updated; the new ETag is in the header and body.
400: Neither title nor content supplied, or malformed body.
412: If-Match does not match the current ETag.
428: If-Match header missing.

Example

Request

curl -X PUT "https://api.testingapis.com/api/cache/etag" \
  -H "Content-Type: application/json" \
  -H "If-Match: "doc-v1"" \
  -d '{"title": "Updated title", "content": "New content"}' \
  -H "X-TestingApis-Key: YOUR_API_KEY"

Response200 OK

ETag: "doc-v2"

{
  "message": "Document updated",
  "data": {
    "id": 1,
    "version": 2,
    "title": "Updated title",
    "content": "New content",
    "updatedAt": "2026-09-30T18:26:44Z",
    "etag": "\"doc-v2\""
  }
}

The parameters, request and response examples and the live Try it panel for this endpoint are for signed-in members. Accounts are free and take a few seconds to create.

Try itSign-in requiredUses your key

api.testingapis.com

curl -X PUT 'https://api.testingapis.com/api/cache/etag' \
  -H 'If-Match: doc-v1' \
  -H 'Content-Type: application/json' \
  -H 'X-TestingApis-Key: YOUR_API_KEY' \
  -d '{"title": "Updated title", "content": "New content"}'

const res = await fetch("https://api.testingapis.com/api/cache/etag", {
  method: "PUT",
  headers: {
    "If-Match": "doc-v1",
    "Content-Type": "application/json",
    "X-TestingApis-Key": "YOUR_API_KEY",
  },
  body: "{\"title\": \"Updated title\", \"content\": \"New content\"}",
});
console.log(res.status, await res.text());

// The shape of the example response in the docs.
type ApiResponse = {
  message: string;
  data: {
    id: number;
    version: number;
    title: string;
    content: string;
    updatedAt: string;
    etag: string;
  };
};

const res = await fetch("https://api.testingapis.com/api/cache/etag", {
  method: "PUT",
  headers: {
    "If-Match": "doc-v1",
    "Content-Type": "application/json",
    "X-TestingApis-Key": "YOUR_API_KEY",
  },
  body: "{\"title\": \"Updated title\", \"content\": \"New content\"}",
});
const body = (await res.json()) as ApiResponse;
console.log(res.status, body);

import requests

res = requests.put(
    "https://api.testingapis.com/api/cache/etag",
    headers={
        "If-Match": "doc-v1",
        "Content-Type": "application/json",
        "X-TestingApis-Key": "YOUR_API_KEY",
    },
    data="{\"title\": \"Updated title\", \"content\": \"New content\"}",
)
print(res.status_code, res.text)

using System.Net.Http.Headers;

using var client = new HttpClient();
using var request = new HttpRequestMessage(HttpMethod.Put, "https://api.testingapis.com/api/cache/etag");
request.Headers.TryAddWithoutValidation("If-Match", "doc-v1");
request.Headers.TryAddWithoutValidation("X-TestingApis-Key", "YOUR_API_KEY");
request.Content = new StringContent("{\"title\": \"Updated title\", \"content\": \"New content\"}");
request.Content.Headers.ContentType = MediaTypeHeaderValue.Parse("application/json");
using var response = await client.SendAsync(request);
Console.WriteLine($"{(int)response.StatusCode} {await response.Content.ReadAsStringAsync()}");

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;

public class Main {
    public static void main(String[] args) throws Exception {
        HttpClient client = HttpClient.newHttpClient();
        HttpRequest request = HttpRequest.newBuilder(URI.create("https://api.testingapis.com/api/cache/etag"))
                .header("If-Match", "doc-v1")
                .header("X-TestingApis-Key", "YOUR_API_KEY")
                .header("Content-Type", "application/json")
                .method("PUT", HttpRequest.BodyPublishers.ofString("{\"title\": \"Updated title\", \"content\": \"New content\"}"))
                .build();
        HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
        System.out.println(response.statusCode() + " " + response.body());
    }
}

package main

import (
	"fmt"
	"io"
	"net/http"
	"strings"
)

func main() {
	body := strings.NewReader("{\"title\": \"Updated title\", \"content\": \"New content\"}")
	req, err := http.NewRequest("PUT", "https://api.testingapis.com/api/cache/etag", body)
	if err != nil {
		panic(err)
	}
	req.Header.Set("If-Match", "doc-v1")
	req.Header.Set("X-TestingApis-Key", "YOUR_API_KEY")
	req.Header.Set("Content-Type", "application/json")
	res, err := http.DefaultClient.Do(req)
	if err != nil {
		panic(err)
	}
	defer res.Body.Close()
	data, err := io.ReadAll(res.Body)
	if err != nil {
		panic(err)
	}
	fmt.Println(res.StatusCode, string(data))
}

PUThttps://api.testingapis.com/api/cache/etag

Query

Headers

If-Matchstring