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How to Verify

As shown in the Why Verify section, verifying incoming webhooks is very important. This section describes how to do it.

Verifying using our official libraries

First install the libraries if you haven't already:

npm install svix
// Or
yarn add svix

Then verify webhooks using the code below. The payload is the raw (string) body of the request, and the headers are the headers passed in the request.

Use the raw request body

You need to use the raw request body when verifying webhooks, as the cryptographic signature is sensitive to even the slightest changes. You should watch out for frameworks that parse the request as JSON and then strigify it because this too will break the signature verification.

See examples below for how to get the raw request body with different frameworks.

The signature you should get from where you added the endpoint, e.g. the application portal.

import { Webhook } from "svix";

const secret = "whsec_MfKQ9r8GKYqrTwjUPD8ILPZIo2LaLaSw";

// These were all sent from the server
const headers = {
"svix-id": "msg_p5jXN8AQM9LWM0D4loKWxJek",
"svix-timestamp": "1614265330",
"svix-signature": "v1,g0hM9SsE+OTPJTGt/tmIKtSyZlE3uFJELVlNIOLJ1OE=",
};
const payload = '{"test": 2432232314}';

const wh = new Webhook(secret);
// Throws on error, returns the verified content on success
const payload = wh.verify(payload, headers);

Framework specific examples

Here are examples on how to adjust the above examples to your favourite framework!

Python (Django)

from django.http import HttpResponse

from svix.webhooks import Webhook, WebhookVerificationError

secret = "whsec_MfKQ9r8GKYqrTwjUPD8ILPZIo2LaLaSw"

@csrf_exempt
def webhook_handler(request):
headers = request.headers
payload = request.body

try:
wh = Webhook(secret)
msg = wh.verify(payload, headers)
except WebhookVerificationError as e:
return HttpResponse(status=400)

# Do someting with the message...

return HttpResponse(status=204)

Python (Flask)

from flask import request

from svix.webhooks import Webhook, WebhookVerificationError

secret = "whsec_MfKQ9r8GKYqrTwjUPD8ILPZIo2LaLaSw"

@app.route('/webhook/')
def webhook_handler():
headers = request.headers
payload = request.get_data()

try:
wh = Webhook(secret)
msg = wh.verify(payload, headers)
except WebhookVerificationError as e:
return ('', 400)

# Do someting with the message...

return ('', 204)

Python (FastAPI)

from fastapi import Request, Response, status

from svix.webhooks import Webhook, WebhookVerificationError

secret = "whsec_MfKQ9r8GKYqrTwjUPD8ILPZIo2LaLaSw"

@router.post("/webhook/", status_code=status.HTTP_204_NO_CONTENT)
async def webhook_handler(request: Request, response: Response):
headers = request.headers
payload = await request.body()

try:
wh = Webhook(secret)
msg = wh.verify(payload, headers)
except WebhookVerificationError as e:
response.status_code = status.HTTP_400_BAD_REQUEST
return

# Do someting with the message...

Node.js (Next.js)

import { Webhook } from "svix";
import { buffer } from "micro";

export const config = {
api: {
bodyParser: false,
},
}

const secret = "whsec_MfKQ9r8GKYqrTwjUPD8ILPZIo2LaLaSw";

export default async function handler(req, res) {
const payload = (await buffer(req)).toString();
const headers = req.headers;

const wh = new Webhook(secret);
let msg;
try {
msg = wh.verify(payload, headers);
} catch (err) {
res.status(400).json({});
}

// Do something with the message...

res.json({});
}

Node.js (Netlify Functions)

import { Webhook } from "svix";

const secret = "whsec_MfKQ9r8GKYqrTwjUPD8ILPZIo2LaLaSw";


export const handler = async ({body, headers}) => {
const payload = body;

const wh = new Webhook(secret);
let msg;
try {
msg = wh.verify(payload, headers);
} catch (err) {
res.status(400).json({});
}

// Do something with the message...

res.json({});
}

Node.js (Express)

import { Webhook } from "svix";
import bodyParser from "body-parser";

const secret = "whsec_MfKQ9r8GKYqrTwjUPD8ILPZIo2LaLaSw";

app.post('/webhook', bodyParser.raw({type: 'application/json'}), (req, res) => {
const payload = req.body;
const headers = req.headers;

const wh = new Webhook(secret);
let msg;
try {
msg = wh.verify(payload, headers);
} catch (err) {
res.status(400).json({});
}

// Do something with the message...

res.json({});
});

Go (Standard lib)

package main

import (
"io"
"log"
"net/http"

svix "github.com/svix/svix-webhooks/go"
)

const secret = "whsec_MfKQ9r8GKYqrTwjUPD8ILPZIo2LaLaSw"

func main() {

wh, err := svix.NewWebhook(secret)
if err != nil {
log.Fatal(err)
}

http.HandleFunc("/webhook", func(w http.ResponseWriter, r *http.Request) {
headers := r.Header
payload, err := io.ReadAll(r.Body)
if err != nil {
w.WriteHeader(http.StatusBadRequest)
return
}

err = wh.Verify(payload, headers)
if err != nil {
w.WriteHeader(http.StatusBadRequest)
return
}

// Do something with the message...

w.WriteHeader(http.StatusNoContent)

})
http.ListenAndServe(":8080", nil)
}

Go (Gin)

package main

import (
"io"
"log"
"net/http"

"github.com/gin-gonic/gin"
svix "github.com/svix/svix-webhooks/go"
)

const secret = "whsec_MfKQ9r8GKYqrTwjUPD8ILPZIo2LaLaSw"

func main() {

wh, err := svix.NewWebhook(secret)
if err != nil {
log.Fatal(err)
}

r := gin.Default()
r.POST("/webhook", func(c *gin.Context) {
headers := c.Request.Header
payload, err := io.ReadAll(c.Request.Body)
if err != nil {
c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
return
}

err = wh.Verify(payload, headers)
if err != nil {
c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
return
}

// Do something with the message...

c.JSON(200, gin.H{})
})
r.Run()
}

Ruby (Ruby on Rails)

Once you've setup your project add a route to your config/routes.rb file at the top of the Rails.application.routes.draw block:

Rails.application.routes.draw do
post "/webhook", to: "webhook#index"

# For details on the DSL available within this file, see https://guides.rubyonrails.org/routing.html
end

The route above declares that POST /webhook requests are mapped to the index action of WebhookController.

To create WebhookController and its index action, we'll run the controller generator (with the --skip-routes option because we already have an appropriate route):

bin/rails generate controller Webhook index --skip-routes

Rails will create several files for you:

    create  app/controllers/webhook_controller.rb
invoke erb
create app/views/webhook
create app/views/webhook/index.html.erb
invoke test_unit
create test/controllers/webhook_controller_test.rb
invoke helper
create app/helpers/webhook_helper.rb
invoke test_unit
invoke assets
invoke scss
create app/assets/stylesheets/webhook.scss

Now we can add our verification logic to the newly created app/controllers/webhook_controller.rb file:

require 'svix'

class WebhookController < ApplicationController
protect_from_forgery with: :null_session # disables CSRF middleware; required for API endpoints

def index
begin
payload = request.body.read
headers = request.headers
wh = Svix::Webhook.new("whsec_MfKQ9r8GKYqrTwjUPD8ILPZIo2LaLaSw")

json = wh.verify(payload, headers)

# Do something with the message...

head :no_content
rescue
head :bad_request
end
end
end

PHP (Laravel)

In your routes/api.php file add the following after the last use directive:

use Svix\Webhook;
use Svix\Exception\WebhookVerificationException;

Route::post('webhook', function(Request $request) {
$payload = $request->getContent();
$headers = collect($request->headers->all())->transform(function ($item) {
return $item[0];
});

try {
$wh = new Webhook("whsec_MfKQ9r8GKYqrTwjUPD8ILPZIo2LaLaSw");
$json = $wh->verify($payload, $headers);

# Do something with the message...

return response()->noContent();
} catch (WebhookVerificationException $e) {
return response(null, 400);
}
});