Onion Browser is a free, open-source Tor-powered web browser for iPhone and iPad, distributed on the App Store since 2012 by developer Mike Tigas through his company Tigas Ventures, LLC, with Benjamin Erhart and the Guardian Project named as main contributors and development funded by donations and optional in-app tips. Its privacy policy states the app does not directly collect any data on user activity and uses no third-party analytics beyond Apple's opt-in aggregated iOS analytics, and the App Store listing carries a "Data Not Collected" label. The Tor Project's support site recommends it as the iOS option, and Privacy Guides lists it, but both — and the developer's own FAQ — document a structural limitation: Apple forces WebKit, so the app cannot ship Tor Browser's Gecko-based fingerprinting and anti-tracking defenses, only tunnels traffic within the app, and in built-in-Tor mode (without the Orbot companion app) leaks the real IP via WebRTC and media streams. The developer self-publishes leak advisories and patches; in August 2026 third-party researchers (Mysk) disclosed further WebKit proxy-bypass leaks affecting iOS Tor browsers, and version 3.4.1 shipped a fix for the DNS-prefetch leak. No independent security audit, breach, or regulatory action involving Onion Browser was found in this research.
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Onion Browser's App Store listing (seller: Mike Tigas) carries Apple's "Data Not Collected" privacy label — the developer declares the app collects no data — and the app is free, with optional in-app "tip" purchases ($0.99, $4.99, $9.99) as its only paid items. Apple notes the label is developer-declared and not verified by Apple.
Onion Browser's privacy policy states the app does not directly collect any data on user activity and, other than what is built into iOS, uses no third-party analytics; the only analytics it references is Apple's opt-in, aggregated iOS analytics, to which the developers say they have no individual-level access. No account, sign-up, or profile is described anywhere in the policy.
The LICENSE file on the repository's default 3.X branch is a bespoke Onion Browser License (copyright Tigas Ventures LLC) built on the BSD-style Endless license: it permits redistribution in source form and use in binary form, but does not grant redistribution in binary form — a source-available arrangement rather than an OSI-approved open-source license, which limits how freely third parties may republish builds of the app.
Onion Browser's Legal page identifies the owner as Tigas Ventures, LLC (holder of the copyright and the "Onion Browser" trademark), states that 1.X was distributed under the Mozilla Public License 2.0 while 2.X and newer ship under the custom "Endless / Onion Browser License" (OBL), and expressly disclaims any affiliation with or endorsement by The Tor Project — even though the Tor Project's own support page recommends the app. No corporate registry, jurisdiction, or officer information for the LLC is published on the site.
Onion Browser's homepage states the app is free and open source, that anyone may contribute, audit or inspect the code, and names its main contributing programmers as Mike Tigas, Benjamin Erhart and Guardian Project; the site footer identifies the copyright holder as Tigas Ventures, LLC, and development is funded by donations.
A 2016-12-06 Tor Project blog post written by the developer describes Onion Browser as an independent community project available since 2012, previously $0.99 and then made free of charge, primarily developed by Mike Tigas (then a developer and journalist at ProPublica) and supported by Patreon backers, other donors, and key support from the Guardian Project — establishing the funding model and the individual-maintainer structure that persist today.
Onion Browser's About page carries a disclaimer that using the app does not by itself guarantee security or privacy: it only tunnels traffic within the Onion Browser app, network traffic outside the app continues over the normal connection, iOS retains full control over some traffic (including audio or video embeds) which may route outside Tor, and websites may use HTML5 geolocation and other features unless "Strict" security mode is set — real exposure paths to websites that exist despite the operator collecting nothing.
Onion Browser's privacy policy describes no first-party data flow to any third party: the only off-device data it references is Apple's iOS analytics, which the policy says is opt-in, aggregated and anonymized with differential privacy, made available by Apple only in aggregate, and not accessible to the Onion Browser developers at an individual level. Because the app collects nothing itself, there is nothing for the operator to share or sell.
Onion Browser's public changelog records a pattern of disclosed and patched leaks: version 3.4.1 fixed the IP leak during DNS prefetch reported by Mysk (noting the other leaks are mitigated by Lockdown Mode in the Silver and Gold security levels), 3.4.0 raised link-preview security to the same level as normal tabs, 3.2.2 fixed a share-sheet leak, 3.2.1 fixed several built-in-Tor leaks, 2.3.0 fixed an OCSP leak and 2.0.2 a DNS leak. Fixes are shipped and documented, but no independent third-party security audit of the app is recorded.
The project self-publishes security advisories on its GitHub wiki; advisory 2018-117 (edited by Mike Tigas, June 2019) documents that iOS handles WebRTC connections outside Onion Browser's control, so WebRTC traffic is not routed over Tor and a site using it would learn the user's real IP address, with the only known mitigation being "Strict" security mode which disables JavaScript.
On 2026-08-04 security researchers Talal Haj Bakry and Tommy Mysk (makers of the competing Psylo browser) published research showing three WebKit features — DNS prefetching, WebAuthn Related Origin Requests, and WebTransport — bypass a proxy configuration and expose the user's real network on iOS proxy browsers including iOS Tor browsers; they state they contacted the Tor Project and the Onion Browser developers, and note Onion Browser's "Silver" security level (Lockdown Mode) already blocked the WebTransport leak.
Onion Browser's FAQ discloses the central technical limitation of the product: Apple requires all iOS browsers to use its WebKit engine, so Onion Browser cannot ship the Firefox/Gecko-based anti-tracking and fingerprinting defenses that Tor Browser has on desktop and Android. The FAQ says the app instead relies on looking like every other iOS WebKit user, forgets everything when backgrounded, keeps no caches or cookies by default, and lets users deny JavaScript per site; it also warns that in built-in-Tor mode (without Orbot) the real IP address leaks to websites via WebRTC and audio/video streams are not tunneled through Tor.
The Tor Project's own support documentation states there is no Tor Browser for iOS and recommends Onion Browser as open source, Tor-routed, and developed by someone who works closely with the Tor Project — while explicitly cautioning that Apple's WebKit requirement prevents Onion Browser from having the same privacy protections as Tor Browser.
Privacy Guides lists Onion Browser on its Tor Browser recommendations page as the iOS option, describing it as open source and endorsed by the Tor Project, with the stated caveats that it does not provide the same privacy protections as desktop Tor Browser, that the built-in Tor mode leaks the real IP via WebRTC and audio/video streams due to WebKit, and that pairing it with Orbot is safer.