curl Online — HTTP Request Tester

What is this tool?

Spoold's curl Online / HTTP request tester is a free browser API client built around real curl commands. Paste a curl string from DevTools ("Copy as cURL"), a README, Postman/Insomnia export, or Slack—then review a live breakdown (method, URL, query, headers, body, auth, cookies, flags) and click Send to run it through Spoold's proxy.

The workspace uses a resizable layout: on the left, curl command and Inspector sit in the same row; on the right, a dedicated Response panel shows status, timing, and a syntax-highlighted body. No install, no sign-up, and no terminal—same intent people mean by test curl online, execute curl online, or online HTTP client.

Why use curl online?

Terminals and desktop clients are great—but often you just need a one-off check: does this endpoint return 200? Is the bearer token still valid? What does the JSON look like? Searching curl online or curl request online usually means: paste what you already have and fire it without fighting CORS or installing Postman.

Spoold runs the outbound call server-side, so public APIs that omit Access-Control-Allow-Origin still respond. Parsing stays in your browser until you click Send.

Features

• Two-on-left + response — curl command and Inspector share the left row; Response stays on the right. Drag the dividers to resize either boundary.
• Editable Inspector — Change method, URL, query, headers, auth, cookies, body, and flags like Postman; edits sync back into the curl command automatically.
• Response panel — Status, latency, byte size, Monaco body with search/copy; JSON pretty-printed when possible.
• Proxy send — Bypass browser CORS for allowed public hosts (SSRF rules block localhost / private IPs).
• Shared parser — Same curl parser as curl Viewer, curl → code, and curl Compare.
• JSON pretty-print — Response bodies that parse as JSON are formatted for reading.

How to use

1. Open curl Online / HTTP Request (or pick a sample from the Samples menu).
2. Paste your curl into the left curl command editor. Multi-line DevTools exports are fine.
3. Skim the middle Inspector—confirm method, URL, headers, and body before anything leaves the browser.
4. Click Send next to the method badge. The Response panel opens with status, timing, and body.
5. Use Search/Copy on the response, or Close to hide the panel and reclaim space.

What the curl breakdown shows

Parsing is client-side and live: as you edit the command, the Inspector updates. If the command cannot be parsed, an error appears in the Inspector—nothing is sent until parsing succeeds and you click Send.

• Method & URL — Including base URL without query noise when the URL parses.
• Query parameters — Key/value table from the request URL.
• Headers — Every -H / --header pair.
• Auth & cookies — Basic auth user (password masked) and cookie jar text when present.
• Body — -d / --data payload, with JSON pretty-printed when possible.
• Flags — -L (follow redirects), -k (insecure TLS), and --compressed are honored on Send by the proxy (redirect hops are re-checked for SSRF).

Sending requests & reading the response

When you click Send, the browser POSTs the parsed URL, method, headers, body, and flags to Spoold's /api/curl-fetch route. The Node proxy issues the real outbound HTTP request and returns status, response headers, body bytes, and timing. Private / metadata hosts are blocked, including after redirects.

The right panel shows success (status color, duration, bytes) with Body and Headers tabs, or a clear error (blocked host, network failure, invalid target). Binary responses are summarized by size rather than dumped as text. Bodies over 5 MB are truncated and clearly marked.

Use cases

• DevTools → verify — Copy as cURL from Chrome/Firefox Network, paste, Send, confirm status without leaving the browser.
• API doc smoke test — Run example curls from OpenAPI/README samples against staging.
• Auth debugging — Check whether a bearer or basic-auth header still returns 200 vs 401.
• Webhook / callback checks — Hit a public echo endpoint (e.g. httpbin) to validate payload shape.
• Support / triage — Reproduce a customer-reported curl and share the status + body snippet.

vs curl Viewer, Postman & Hoppscotch

Limits & privacy

• SSRF protection — Localhost, private, and link-local targets are blocked. Only publicly reachable HTTP(S) hosts are allowed.
• Secrets — Treat the Send path like any proxy: do not paste production credentials on a shared machine. Prefer staging tokens.
• Parser coverage — Common curl flags are supported; exotic options may not map 1:1. Use the breakdown to see what will actually be sent.
• Body size — Very large or binary responses may be truncated or summarized.
• No silent upload — Parsing stays local. Network I/O happens only when you click Send.

FAQ

Related terms

Run & test: curl online, online curl, test curl online, curl test online, execute curl online, run curl online, curl request online, curl checker, online curl tool.

HTTP clients: online http client, http request tester, api tester online, rest client online, send http request online, browser http client, online rest client.

Workflows: copy as curl chrome, copy as curl firefox, paste curl from devtools, test bearer token curl, test basic auth curl, api request debugger.

Pair with Spoold's curl Viewer (inspect), curl Compare (diff), curl → code (codegen), and HTTP status codes when you need the meaning of a status line.

Similar tools

Other Spoold utilities that pair with curl online:

• curl Viewer
• curl Compare
• curl Converter
• HTTP Status Codes
• URL Inspector
• JSON Formatter

Conclusion

Use this curl online tool when you want the shortest path from a pasted command to a real response: breakdown on the left, status and body on the right. For richer inspection use curl Viewer; to diff two requests use curl Compare; to turn a curl into code use the curl → code converter.