Build vs Buy Webhook Infrastructure
When building webhook handling and delivery stops being "just an endpoint and a retry loop".
A practical, technical breakdown for engineers evaluating their options.
Why Teams Consider Building Webhook Infrastructure
At first glance, webhooks seem straightforward. You need an HTTP endpoint, some signature verification, and a retry mechanism. How hard could it be?
This reasoning is not unreasonable. Early on, webhook volume is low. Your team already has message queues and background workers. You want control over your infrastructure. Building feels like the obvious choice.
For many teams, this initial assessment is correct. A simple webhook system can work well for months or even years, especially if your requirements remain constrained.
The question is not whether building is possible. It is whether the ongoing cost remains acceptable as requirements evolve.
What a "Simple" Webhook System Looks Like
The typical first implementation includes:
HTTP Endpoint
A POST handler that receives webhook payloads from external services.
Signature Verification
HMAC validation to ensure requests are authentic.
Background Job
Queue the payload for asynchronous processing.
Basic Retries
Retry failed deliveries a few times before giving up.
Logging
Basic request/response logging for debugging.
This works. For a while.
What Gets Added After the First Incident
Production requirements emerge after the first failure. What started as a simple system accumulates complexity.
Inbound Requirements
Backpressure Handling
When a webhook source sends faster than you can process, you need rate limiting, queue depth monitoring, and graceful degradation.
Payload Inspection and Filtering
Not all events are relevant. You need to inspect, filter, and route based on payload content without processing everything.
Transformation
External webhook formats rarely match your internal schemas. Transformation logic accumulates over time.
Replay Without Re-Sending
When debugging or recovering from failures, you need to replay events without asking the sender to re-send them.
Per-Source Isolation
One misbehaving webhook source should not affect others. Isolation requires separate queues, rate limits, and failure tracking.
Outbound Requirements
Per-Destination Retries
Each destination has different reliability characteristics. Retry strategies must be configurable per endpoint.
Backoff Strategies
Exponential backoff, jitter, circuit breakers, and dead letter queues become necessary to handle persistent failures.
Fan-Out
A single inbound event often needs to be delivered to multiple destinations. Fan-out multiplies failure modes.
Partial Failure Handling
When delivering to multiple destinations, some succeed and some fail. You need to track partial success and retry only failures.
Customer-Level Isolation
In multi-tenant systems, one customer's failing endpoint should not affect others. Isolation is non-trivial.
Operational Requirements
Dashboards and Observability
You need visibility into delivery rates, failure rates, retry queues, and latency across all sources and destinations.
Manual Intervention
Operators need tools to pause, resume, purge, or manually retry specific events or entire queues.
Alerts and On-Call
Webhook failures require alerting, escalation policies, and runbooks. Someone gets paged when things break.
Audit Logs
For compliance and debugging, you need immutable logs of every webhook received, processed, and delivered.
Schema and Version Drift
External APIs change. You need versioning, schema validation, and migration strategies to handle breaking changes.
Complexity compounds over time. Each requirement adds code, tests, monitoring, and maintenance burden.
Hidden Costs Teams Underestimate
The initial build is only the beginning. Ongoing costs are often underestimated.
Ongoing Engineering Maintenance
Webhook infrastructure is not a one-time project. External APIs change, new edge cases emerge, and performance optimization is continuous. Engineers spend time maintaining code that does not differentiate your product.
Edge Cases and Failure Modes
Distributed systems have unbounded failure modes. Timeouts, partial failures, duplicate deliveries, ordering issues, and clock skew all require handling. Each edge case takes time to discover, reproduce, and fix.
On-Call Burden
Webhook failures often happen outside business hours. Someone gets paged. Runbooks need to be written and maintained. Incident response takes time away from planned work.
Knowledge Silos
Webhook infrastructure becomes tribal knowledge. The engineer who built it understands it. When they leave, the next person has to reverse-engineer the system. Documentation lags behind reality.
Opportunity Cost
Every hour spent on webhook infrastructure is an hour not spent on your core product. This is the most significant cost and the hardest to measure.
Why Webhooks Are Harder Than They Look
Webhooks are uniquely difficult because they operate at system boundaries.
System Boundary Problem
Webhooks cross organizational and technical boundaries. You do not control the sender or the receiver. This fundamentally changes the failure model compared to internal services.
No Control Over Sender or Receiver
External services have their own rate limits, downtime, and breaking changes. Destination endpoints have unpredictable latency and availability. You cannot fix problems on either side.
Retries Amplify Failures
A naive retry strategy can make problems worse. Retrying too aggressively overwhelms failing systems. Retrying too conservatively loses data. Finding the right balance requires tuning and monitoring.
Timeouts Are Unreliable
Network timeouts do not tell you whether the request succeeded. The destination might have processed the webhook even if you did not receive a response. Idempotency becomes critical.
Fan-Out Multiplies Complexity
Delivering one event to multiple destinations means multiple independent failure modes. Partial success is common. Tracking state across fan-out is non-trivial.
When Building Makes Sense
Building in-house is reasonable in specific scenarios.
Very Low Volume
If you receive or send fewer than a few hundred webhooks per day, complexity remains manageable.
Internal-Only Usage
If webhooks are only used internally between services you control, you can coordinate changes and tolerate downtime.
Single Consumer
If you only deliver to one destination, fan-out complexity disappears. Failure handling is simpler.
No Replay or Fan-Out Needs
If you never need to replay events or deliver to multiple destinations, the system remains straightforward.
No SLAs or External Customers
If webhook delivery is best-effort and failures do not affect customers, operational burden is lower.
If your use case fits these constraints, building may be the right choice.
When Buying Makes Sense
Certain signals indicate that a managed solution becomes more cost-effective than building.
Multiple Webhook Sources
Each external webhook source has different authentication, payload formats, and reliability characteristics. Managing multiple sources multiplies complexity.
External Customers or Partners
When customers or partners depend on webhook delivery, reliability becomes a contractual obligation. Failures affect relationships and revenue.
Reliability Requirements
If you need guaranteed delivery, retry guarantees, or SLAs, building and maintaining the necessary infrastructure is expensive.
Need for Replay and Observability
Debugging webhook issues requires detailed logs, replay capabilities, and visibility into delivery status. Building these tools takes significant time.
Multiple Delivery Destinations
Fan-out to multiple destinations introduces partial failure handling, per-destination retries, and isolation requirements. This is where complexity escalates quickly.
When these conditions apply, the total cost of ownership for a custom solution often exceeds the cost of a managed service.
Where hookVM Fits
hookVM operates as a control plane at the boundary of your system.
Rather than replacing your entire webhook infrastructure, hookVM provides the capabilities that are expensive to build and maintain in-house.
For inbound webhooks, hookVM handles safe ingestion, inspection, filtering, transformation, and replay without re-sending. You get isolation per source and visibility into what is being received.
For outbound webhooks, hookVM manages delivery to multiple destinations with per-destination retries, backoff strategies, and partial failure handling. Customer-level isolation ensures one failing endpoint does not affect others.
Observability is built in. You can see delivery status, retry queues, and failure rates without building dashboards or alerting infrastructure.
Safe Inbound Handling
Receive webhooks from external sources with signature verification, rate limiting, and backpressure handling.
Inspection and Filtering
Examine payloads, filter events, and transform formats before they reach your internal systems.
Replay Without Re-Sending
Replay events for debugging or recovery without asking external services to re-send them.
Outbound Delivery
Deliver events to multiple destinations with retries, backoff, and failure isolation.
Isolation and Observability
Per-source and per-destination isolation with detailed visibility into delivery status and failures.
Build vs Buy Comparison
| Capability | Build In-House | Managed Solution |
|---|---|---|
| Inbound Isolation | Requires custom queue architecture | Built-in per-source isolation |
| Replay | Must store and index all payloads | Replay from stored events |
| Fan-Out | Complex partial failure handling | Managed fan-out with per-destination tracking |
| Destination Retries | Custom retry logic per destination | Configurable retry strategies |
| Observability | Build dashboards and alerting | Built-in visibility and logs |
| Ongoing Maintenance | Continuous engineering time | Vendor maintains infrastructure |
Migration and Incremental Adoption
Adopting a managed solution does not require rewriting your existing webhook infrastructure.
Start with Inbound Debugging
Route inbound webhooks through hookVM for inspection and replay capabilities while keeping your existing processing logic unchanged.
Add Outbound Destinations Later
When you need to deliver to multiple destinations, add them incrementally without changing your event publishing code.
Keep Existing Webhooks
Your current webhook endpoints continue to work. Migrate sources and destinations one at a time as needed.
Adopt Incrementally
Use hookVM for new webhook sources or destinations while leaving stable, low-volume webhooks unchanged.
Incremental adoption reduces risk and allows you to validate the solution before committing fully.
Focus on Your Product, Not Webhook Plumbing
If webhook reliability and delivery are becoming a distraction, hookVM provides control at your system boundaries without forcing a rewrite.