What is a Webhook? Why Your Team Should Stop Building Them

So what is a webhook? In short, it is an HTTP callback that pushes data between apps when events happen. You set up a webhook from Stripe to HubSpot. A customer upgrades their plan, Stripe fires an event, HubSpot gets the update. It works perfectly for six months. Then Stripe changes their payload schema, your webhook handler silently starts dropping events, and your CRM shows three paying customers as "Free plan" for two weeks before anyone notices.

This is not an edge case. It is the default outcome of webhook-based integrations maintained by teams without a dedicated integration engineer.

What a webhook is and how webhook event-driven data flow works

A webhook is an HTTP callback. When an event occurs in one application (the sender), that application makes an HTTP POST request to a URL you've registered (the receiver). The POST body contains a JSON payload describing the event.

The concept is simple: instead of your app repeatedly asking "did anything change?" (polling), the source app tells you when something changes (pushing). This is event-driven data flow, and the concept is sound. Polling wastes API calls checking for changes that haven't happened. Webhooks only fire when there's something to report.

Here's what a typical Stripe webhook payload looks like when a customer's subscription changes:

{
  "type": "customer.subscription.updated",
  "data": {
    "object": {
      "id": "sub_1234",
      "customer": "cus_5678",
      "status": "active",
      "items": {
        "data": [{ "plan": { "nickname": "Team" } }]
      }
    },
    "previous_attributes": {
      "items": {
        "data": [{ "plan": { "nickname": "Free" } }]
      }
    }
  }
}

{
  "type": "customer.subscription.updated",
  "data": {
    "object": {
      "id": "sub_1234",
      "customer": "cus_5678",
      "status": "active",
      "items": {
        "data": [{ "plan": { "nickname": "Team" } }]
      }
    },
    "previous_attributes": {
      "items": {
        "data": [{ "plan": { "nickname": "Free" } }]
      }
    }
  }
}

{
  "type": "customer.subscription.updated",
  "data": {
    "object": {
      "id": "sub_1234",
      "customer": "cus_5678",
      "status": "active",
      "items": {
        "data": [{ "plan": { "nickname": "Team" } }]
      }
    },
    "previous_attributes": {
      "items": {
        "data": [{ "plan": { "nickname": "Free" } }]
      }
    }
  }
}

Your receiver endpoint parses this JSON, extracts the fields you care about, and writes them to your destination (a CRM, a database, a support tool). That's the theory. The practice is where things get complicated.

Webhook vs API: when to push data and when to pull it

The "webhook vs API" framing that most guides use is misleading. Webhooks and APIs aren't alternatives. They're complementary patterns that solve different problems.

Use an API when you need to query data on demand, run bulk exports, or control exactly when data flows. APIs give you pagination, filtering, and error handling you control.

Use a webhook when you need to react to events as they happen: a payment succeeds, a ticket is created, a form is submitted. Webhooks give you speed.

Use managed sync when you need two tools to stay continuously in sync. This is the category most teams actually need but don't realize exists. You don't need to react to individual Stripe events. You need your CRM to always reflect current Stripe data.

The mistake most teams make: they reach for webhooks when what they actually need is ongoing data synchronization. A webhook handles one event at a time. Synchronization handles the entire dataset, including backfills, updates, deletes, and retries.

Why webhooks break: reliability, retries, and the maintenance nobody signs up for

Webhooks have a fundamental reliability problem. The HTTP POST is fire-and-forget from the sender's perspective. If your endpoint is down, slow, or returns an error, the sender has limited options.

No delivery guarantees. There is no standard webhook specification. Each sender implements retries differently. Stripe retries up to 3 times over a few hours. GitHub retries for up to 3 days. Some services don't retry at all. If your endpoint misses an event, that data is gone unless you build recovery yourself.

No ordering guarantees. If Stripe fires three events for the same customer within a second, they may arrive at your endpoint out of order. Your handler needs to be idempotent and handle event sequencing, or you'll overwrite new data with old data.

Silent failures are the default. When a webhook fails, nobody gets an alert by default. The sender logs a delivery failure on their side. Your system never received the event, so it has nothing to log. The gap between "data should have arrived" and "data didn't arrive" is invisible until a human notices stale records.

Schema changes break everything. Webhook payloads change when the sender updates their API. A field gets renamed, a nested object gets restructured, a new required field appears. Your handler was written to parse the old schema. It either crashes (best case: you find out immediately) or silently drops the new fields (worst case: you find out weeks later).

You're running infrastructure. A webhook receiver is a server endpoint that must be publicly accessible, always available, and fast enough to respond within the sender's timeout window (typically 5-30 seconds). That means hosting, SSL certificates, uptime monitoring, and incident response. For a 5-person team, this is overhead you didn't sign up for.

The irony: webhooks are supposed to reduce complexity compared to polling. In practice, a reliable webhook setup requires retry logic, dead letter queues, signature verification, idempotent processing, schema versioning, and monitoring. That's more infrastructure than the polling approach it replaced.

Webhook alternatives for syncing data between SaaS tools

If your goal is keeping two tools in sync, webhooks are solving the wrong problem at the wrong level of abstraction. You don't need event-by-event push notifications. You need continuous data synchronization with built-in reliability.

Here's what the alternatives look like:

Scheduled API polling. Query the source API every 15 minutes for records that changed since the last run. Simple, reliable, and you control the entire flow. The downside: you write and maintain the polling script, the field mapping logic, and the error handling. For one integration, this is manageable. For five, it's a full-time job.

Glue tools (Zapier, Make). These accept webhooks or poll APIs and map data between tools with a visual builder. They work for simple one-to-one triggers but fall apart at scale: per-task pricing adds up, there's no concept of a "record" (just events), no backfill capability, and no dead letter queue for failed events.

Managed data sync. Connect two tools, map fields, set a schedule, and data flows automatically. The sync engine handles polling, change detection, retries, and error recovery. No webhook endpoint to host, no JSON parsing to write, no schema drift to debug. This is what tools like Oneprofile are built for.

The key difference: webhooks push individual events that you process one at a time. Managed sync operates on records, tracking which fields changed (with old and new values) and syncing only the diff. When a sync fails, the record goes to a dead letter queue for investigation instead of disappearing.

How to get webhook-level freshness without building webhook infrastructure

The reason teams reach for webhooks is speed. They want Stripe data in HubSpot within minutes, not hours. That's a legitimate requirement. But webhook-level freshness doesn't require webhook infrastructure.

Incremental sync running every 15 minutes gives you near-real-time freshness with none of the maintenance burden. Here's the comparison:

For most operational use cases, 15-minute freshness is indistinguishable from real-time. Your support rep doesn't need to see a subscription change within 3 seconds. They need to see it before their next interaction with that customer, which is almost always more than 15 minutes away.

Oneprofile replaces webhook chains with managed sync that includes property-level change tracking, automatic retries, and a dead letter queue for failed records. Connect your tools, map fields, and data flows on a schedule. No endpoint to host, no JSON to parse, no silent failures to debug. Your database or any SaaS tool becomes the source of truth, and every connected destination stays current automatically.

The teams that benefit most are the ones currently maintaining 3-5 webhook integrations with custom handler code, retry logic, and monitoring they built themselves. Replacing that stack with managed sync isn't a trade-off. It's eliminating an entire category of maintenance work that shouldn't exist in the first place.