Terms of use

Version: 1.3 Effective date: 27 July 2026 Applies to: Portwhistle for macOS, version 0.1.0 (build 33), and later builds distributed under these terms. Licensor: the operator of Portwhistle, an independent developer based in India ("we", "us"). Contact: support@portwhistle.com · https://portwhistle.com

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Summary

This box is a plain-language summary. It is not a substitute for the sections below, and if it conflicts with them, they govern.

• Portwhistle is free to download and use for monitoring. Blocking and related enforcement are free for a 30-day trial; after that they need a one-time licence you can buy through our seller, Lemon Squeezy. There is no subscription, no account, and no sign-in.
• You may install it on Macs you own or control, for personal or internal business use. You may not sell it or redistribute it. Sharing the download link is welcome.
• Portwhistle sees who your applications connect to, the process, the destination host or IP address, the port, and byte counts. It cannot read the contents of your encrypted connections. It has no mechanism to decrypt anything.
• It installs a macOS system extension that runs with elevated privileges and is handed every outbound connection your Mac makes. That is what an application firewall requires. Decide about it deliberately.
• This is pre-release software. It may contain defects and may affect network behaviour.
• Use it only on machines you are authorised to monitor. Monitoring other people's traffic without their knowledge may be unlawful where you are.
• It comes with no warranty, and our liability is limited as far as the law allows.

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1. Acceptance

By downloading, installing, or using Portwhistle, you agree to these terms. If you do not agree, do not install it. If you are agreeing on behalf of an organisation, you confirm you are authorised to bind it.

These terms are consistent with the LICENSE file distributed with the application. Where a point is covered in both, they say the same thing; these terms add detail, they do not contradict it.

2. Licence

2.1 Grant. We grant you a personal, non-exclusive, non-transferable, revocable licence to install and use Portwhistle on Macs you own or control, for personal or internal business use. Monitoring is free of charge. Blocking and related enforcement features are free for a 30-day trial; continuing to use them afterwards requires a one-time paid licence key, sold and verified through Lemon Squeezy, our seller of record. No account is needed; you activate a licence by entering its key in the app.

2.1a Payment and refunds. Licence payments, taxes, invoices, and refunds are handled by Lemon Squeezy as the seller of record, under its own terms. The application keeps working whether or not you hold a licence; a licence unlocks the enforcement features described above.

2.2 What is licensed. This licence covers the compiled application only. Portwhistle's source code is not published, and nothing here grants any right to it. The software is licensed, not sold; all rights not expressly granted are reserved.

2.3 Restrictions. You may not sell, rent, lease, sublicense, or redistribute the application or any modified version of it. You may not remove or alter its code signatures, notices, or identifiers.

2.4 Sharing. You may share the download link freely, please do. Please link to the official release rather than re-hosting the file.

2.5 Reverse engineering. You may not reverse engineer, decompile, or disassemble the application, except to the extent that this restriction cannot be excluded under the law that applies to you.

3. What Portwhistle does, and does not do

3.1 What it does. Portwhistle installs a macOS system extension that macOS hands every new outbound connection this Mac makes. For each connection it can see the originating process and its code-signing identity, the remote host name or IP address, the port, and the number of bytes transferred. It shows you this live, lets you allow or deny connections by application or by destination, keeps a local connection history you can view and erase, and looks up the destination's country against a database bundled inside the application.

3.2 It cannot read the contents of your traffic. Portwhistle does not decrypt HTTPS or any other encrypted traffic. It does not attempt to, and it has no mechanism to do so. The extension never asks the operating system for the contents of a connection; it makes an allow-or-deny decision from connection metadata alone. Portwhistle sees who an application connects to, never what is said.

3.3 There is no root certificate authority. Portwhistle does not generate, install, or hold a root certificate. It does not add anything to your system trust store, and it does not store a private key in your Keychain.

3.4 HTTPS content inspection does not exist in this product. Seeing request methods, URLs, headers, or bodies is not built, not shipped, and not partially present. Nothing in these terms grants consent to, or authorises, any decryption of your traffic, because there is nothing to consent to.

4. Risk

4.1 Defects. Portwhistle may contain defects, may behave unexpectedly, and may affect network behaviour on your machine.

4.2 Elevated privileges. It installs a macOS system extension that runs as root and processes every outbound network connection. A defect in privileged software has a wider blast radius than a defect in an ordinary application. Install it deliberately.

4.3 Removal. There is no uninstaller. Removal is a short manual procedure set out on the download page, and your rules and history are left in place unless you delete them yourself.

5. Your responsibilities

5.1 Authorised machines only. You will install and run Portwhistle only on Macs you own or are expressly authorised to administer and to monitor.

5.2 Lawful use. Portwhistle observes and can block network connections. You will not use it to monitor, record, or interfere with another person's network traffic without their knowledge where doing so would be unlawful. Depending on where you are, monitoring another person's communications without their consent or another valid legal basis may breach interception, computer-misuse, privacy, or data-protection law, and may be a criminal offence.

5.3 Organisations and shared machines. If you deploy Portwhistle in an organisation, on machines used by other people, or on shared or managed systems, obtaining any legally required notice, consent, or authorisation is your responsibility, not ours.

5.4 No malicious use. You will not use Portwhistle to attack or disrupt any system, to facilitate malware, or for any fraudulent or illegal purpose.

5.5 Consequences. Breach of this section ends your licence immediately.

6. No warranty

PORTWHISTLE IS PROVIDED "AS IS" AND "AS AVAILABLE", WITH ALL FAULTS AND WITHOUT WARRANTY OF ANY KIND. TO THE MAXIMUM EXTENT PERMITTED BY LAW WE DISCLAIM ALL WARRANTIES, EXPRESS, IMPLIED, OR STATUTORY, INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND NON-INFRINGEMENT.

WE DO NOT WARRANT THAT PORTWHISTLE WILL BLOCK OR REVEAL ANY OR ALL CONNECTIONS, THAT IT WILL ATTRIBUTE EVERY CONNECTION TO THE CORRECT APPLICATION, THAT IT IS ERROR-FREE OR UNINTERRUPTED, THAT DEFECTS WILL BE CORRECTED, OR THAT IT WILL NOT AFFECT THE BEHAVIOUR OF YOUR NETWORK OR OF OTHER SOFTWARE. YOU ASSUME THE RISK OF INSTALLING AND RUNNING PRE-RELEASE PRIVILEGED SOFTWARE.

7. Limitation of liability

TO THE MAXIMUM EXTENT PERMITTED BY LAW, WE WILL NOT BE LIABLE FOR ANY INDIRECT, INCIDENTAL, SPECIAL, CONSEQUENTIAL, EXEMPLARY, OR PUNITIVE DAMAGES, OR FOR ANY LOSS OF PROFITS, REVENUE, DATA, GOODWILL, OR BUSINESS, OR FOR BUSINESS INTERRUPTION, ARISING FROM OR IN CONNECTION WITH PORTWHISTLE OR ITS USE, UNDER ANY THEORY OF LIABILITY, EVEN IF WE HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

TO THE MAXIMUM EXTENT PERMITTED BY LAW, OUR TOTAL AGGREGATE LIABILITY ARISING FROM OR IN CONNECTION WITH PORTWHISTLE AND THESE TERMS IS LIMITED TO THE GREATER OF (A) THE FEES YOU PAID FOR YOUR PORTWHISTLE LICENCE IN THE TWELVE MONTHS BEFORE THE EVENT GIVING RISE TO THE CLAIM, OR (B) WHERE YOU PAID NOTHING, ZERO.

Nothing in these terms excludes or limits any liability that cannot be excluded or limited under the law that applies to you, including, where applicable, liability for death or personal injury caused by negligence, for fraud, or under non-waivable consumer-protection law. If any part of sections 6 or 7 is unenforceable where you are, it applies to the fullest extent that is enforceable, and the rest is unaffected.

8. Privacy

Portwhistle runs on your device. It has no servers, no accounts, and no telemetry. It makes two optional network calls of its own, a licence check and an update check, and neither carries anything about your connections, rules, or history.

It does keep records on your Mac, including a local connection history of the connections your applications make and a local diagnostics log. What is stored, where, for how long, and how to remove it is set out in the Portwhistle Privacy Policy, which is included in full inside the application, you are shown it, and asked to accept it, alongside these terms, and is also published at https://portwhistle.com/legal/privacy. That policy forms part of this agreement by reference, and it, not this section, is the authoritative description. Please read it.

9. Third-party components

9.1 DB-IP. Portwhistle includes the DB-IP IP-to-Country Lite database, used under the Creative Commons Attribution 4.0 International licence (CC BY 4.0): https://creativecommons.org/licenses/by/4.0/. The attribution is displayed on the Map screen in the application. The database is bundled inside the application and read locally; DB-IP is not contacted when you use Portwhistle.

9.2 Open-source libraries. Portwhistle incorporates open-source components, including SQLite (public domain) and the Rust libraries maxminddb, rusqlite, serde, serde_json, thiserror, time, uniffi, pcap, and libc. Each is licensed to you under its own terms, which govern that component. Where such a licence conflicts with these terms in respect of that component, that licence governs for that component only.

9.3 Apple and Lemon Squeezy. Licences are sold and verified through Lemon Squeezy, our seller of record. Your dealings with Apple and with Lemon Squeezy are governed by their own terms and privacy policies, not by these terms. The Privacy Policy explains what that means in practice.

10. Changes to these terms

We may update these terms as Portwhistle changes. Every version is numbered and dated at the top of this document. When either this document or the Privacy Policy changes, Portwhistle asks you to read and accept the new version the next time you open the application; if you decline, it quits and you should remove it. Your acceptance is recorded on your own Mac and is not sent anywhere.

11. Termination

You may stop using Portwhistle at any time by removing it, following the uninstall procedure on the download page. This licence terminates automatically if you breach these terms, or when a later release is accompanied by a superseding licence. Sections 5.2, 6, 7, 9, and 12 survive termination.

12. Governing law

These terms are governed by the laws of India, and the courts of Visakhapatnam, Andhra Pradesh, India have jurisdiction over any dispute arising from them. If you are a consumer, this does not deprive you of the protection of the mandatory law of the country where you live, or of any right you have under local law to bring proceedings there.

13. General

These terms, together with the LICENSE file distributed with the application and the Privacy Policy, are the entire agreement between you and us about Portwhistle, and they replace any earlier draft terms. If any provision is held unenforceable, the rest remains in force. Our failure to enforce a provision is not a waiver of it. You may not assign these terms; we may assign them in connection with a transfer of the product.

14. Contact

Questions about these terms: support@portwhistle.com.

Please report a security-relevant defect privately by email rather than in a public issue.