curl to Dart

What this tool is used for

• Converting an API's curl example into Dart for a Flutter app.
• Reproducing a captured request inside an existing Dart client.
• Getting the header map and body encoding right for a POST.
• Producing a snippet to drop into a repository class.
• Checking which curl flags the http package cannot express.

Frequently Asked Questions

Which client should I use in Flutter?

The package:http Client is the portable choice and works on web, where dart:io is unavailable. dart:io's HttpClient is lower level and native-only — using it breaks a Flutter web build.

Do I need to close the client?

Yes, if you create one: call client.close() when finished, otherwise the underlying connections stay open. The top-level helpers (http.get, http.post) create and close a client per call, which is convenient but gives up connection reuse.

How do I send and decode JSON?

Encode with jsonEncode(map) into body and set the Content-Type header; decode with jsonDecode(response.body). package:http does not do either automatically, and response.body is always a String.

Why do Android release builds fail with a network error?

Android requires the INTERNET permission in AndroidManifest.xml — debug builds add it implicitly, release builds do not. Cleartext HTTP is also blocked by default from Android 9 onwards.

How do I set a timeout?

There is no timeout parameter — chain .timeout(Duration(seconds: 10)) on the returned Future, which throws TimeoutException. dart:io's HttpClient does expose connectionTimeout directly.

Should JSON decoding run on the main isolate?

Not for large payloads — `jsonDecode` is synchronous and blocks the UI thread, dropping frames. `compute()` moves it to a background isolate, which is the standard Flutter fix for a list that stutters while loading.

How is certificate pinning done?

Through `HttpClient.badCertificateCallback`, or a `SecurityContext` with your own trusted certificate. The callback receives the certificate and returns whether to accept it — returning `true` unconditionally disables validation entirely.

Common errors and gotchas

• Forgetting `jsonEncode` on a Map body, which otherwise sends Dart's toString output.
• Omitting the content-type, which the http package does not infer from the body.
• Assuming cookies persist, when the http package has no jar — that needs a client wrapper.
• Not closing the client, which on a long-lived app leaks sockets.
• Expecting a non-2xx to throw, when you must check `statusCode` yourself.