Capture

Capture helps you see real HTTP traffic from partners — payment webhooks, OAuth callbacks, and API callbacks — without building your own receiver.

Create an Inbox, share its catch URL, then inspect every request (headers, body, timing) in Spanline. Set a mock response, replay a request, or export a HAR file for debugging.

Capture inbox with request list, webhook context bar, and request inspector
Capture → Inbox — live request list, catch URL in the context bar, and the request inspector.

How it fits together

You work in… It does…
Spanline app Create Inboxes, inspect traffic, configure mock responses, replay, export HAR
Catch URL (/i/{inbox-id}) Where partners and test clients send HTTP traffic — no sign-in required

Capture has a single console surface in the product rail (no Overview / Scenarios-style scene tabs). Everything happens inside an Inbox.

Tour the product surfaces

Surface URL What you use it for
Inbox console /capture/:inboxId Listen for traffic, client snippets, mock response editor
Request detail /capture/:inboxId/:requestId Inspect body, headers, query, cookies, auth, meta; replay and export
Catch URL https://api.spanline.dev/i/:inboxId Inbound address for webhooks and HTTP clients (not the SPA URL)
Empty Capture inbox with listen hero and curl snippet
Empty Inbox — listen hero, **Send test**, and copy-paste client snippets.

Quick start

New here? Follow Getting started — Inbox → catch URL → inspect.

  1. Sign in at app.spanline.dev and open your workspace.
  2. Open Capture in the product rail (Spanline creates an Inbox if you do not have one yet).
  3. Copy the catch URL from the context bar or Help.
  4. Point your provider’s webhook (or a test client) at that URL.
  5. Watch requests appear live in the sidebar; open one to inspect.
curl -X POST "https://api.spanline.dev/i/<your-inbox-id>" \
  -H "Content-Type: application/json" \
  -d '{"hello":"world"}'

Tip: The catch URL is what partners call. The page you use in the app (/capture/…) is only for people on your team.

What you can do today

Capability Where
Inspect requests Capture → open an Inbox → select a request
Set a mock response Response tab in the console
Replay a request Request detail → Replay / Edit & Replay
Compare two requests Request detail → Compare
Export HAR Request detail → export menu
Client snippets Empty Inbox or Help
Link to a Project New Inbox modal in the product
Clean up Sidebar menu — delete one request, clear all, or destroy Inbox

In this guide

Page Contents
Getting started First capture end to end
Concepts Inbox, catch URL, what is stored
Guides Create, inspect, mock, replay, export
Privacy & safety Secrets in captures, sharing tips
FAQ Common problems