Neynar webhooks are a way to receive real-time updates about events on the Farcaster protocol. You can use webhooks to build integrations that respond to events on the protocol, such as when a user creates a cast or when a user updates their profile. This guide will show you how to set up a webhook in the Neynar developer portal and how to integrate it into your application. First, log in to the Neynar developer portal and navigate to the “Webhooks” tab. Click the “Create Webhook” button to create a new webhook.
create webhook
The webhook will fire to the specified target_url. To test it out, we can use a service like ngrok to create a public URL that will forward requests to your local server. Let’s create a simple server that logs out the event. We will be using Bun JavaScript. 
Bun.serve({
  async fetch(req) {
    console.log(await req.json());
    return new Response("Neynar webhook!");
  },
});
Next: run bun serve index.ts, and run ngrok with ngrok http 3000. Copy the ngrok URL and paste it into the “Target URL” field in the Neynar developer portal.
create webhook
Here, we setup a webhook that fires to that ngrok endpoint (which is hooked to our localhost:3000), and the webhook will fire when a cast is made in the Memes channel. Now the server will log out the event when it is fired. It will look something like this: 
{
  created_at: 1708025006,
  type: "cast.created",
  data: {
    object: "cast",
    hash: "0xfe7908021a4c0d36d5f7359975f4bf6eb9fbd6f2",
    thread_hash: "0xfe7908021a4c0d36d5f7359975f4bf6eb9fbd6f2",
    parent_hash: null,
    parent_url: "chain://eip155:1/erc721:0xfd8427165df67df6d7fd689ae67c8ebf56d9ca61",
    root_parent_url: "chain://eip155:1/erc721:0xfd8427165df67df6d7fd689ae67c8ebf56d9ca61",
    parent_author: {
      fid: null,
    },
    author: {
      object: "user",
      fid: 234506,
      custody_address: "0x3ee6076e78c6413c8a3e1f073db01f87b63923b0",
      username: "balzgolf",
      display_name: "Balzgolf",
      pfp_url: "https://i.imgur.com/U7ce6gU.jpg",
      profile: [Object ...],
      follower_count: 65,
      following_count: 110,
      verifications: [ "0x8c16c47095a003b726ce8deffc39ee9cb1b9f124" ],
      active_status: "inactive",
    },
    text: "LFG",
    timestamp: "2024-02-15T19:23:22.000Z",
    embeds: [],
    reactions: {
      likes: [],
      recasts: [],
    },
    replies: {
      count: 0,
    },
    mentioned_profiles: [],
  },
}
That’s it, it’s that simple! Next steps would be to have a public server that can handle the webhook events and use it to suit your needs. Note: Webhook events might be delayed at times of heavy load or when it’s first created from the dev portal.

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