Zero Knowledge Sieve Tool

Sieve Filter Generator and Tester

Build, inspect, and test Sieve filters locally in the browser. Nothing is sent to or stored on a server.

Privacy

The builder, parser, evaluator, and `.eml` import all run entirely on the client side.

Rule name Logic for multiple conditions

Define when the filter should trigger.

Choose what should happen when a message matches.

The generator and tester are aligned with Proton's officially documented list of supported Sieve actions and tests.

Sieve filter

Paste the full raw message or load a local `.eml` file.

Load local `.eml`

Raw email

Advanced test data

Simulated current time Current flags Envelope-From Envelope-To Current expiration time External lists as JSON

Build filters with a guided form