Otter Browser user agent
Otter Browser is an open-source project that aims to recreate the look and feel of the classic, pre-Chromium Opera. It is built on a web engine and presents a user agent shaped by that engine, sometimes with an Otter token. It is a low-volume, legitimate human browser rather than any kind of automated client.
What this means
Otter Browser is a community project recreating the classic Opera interface from before Opera moved to Chromium. It is built on a web engine and is aimed at users who want that earlier Opera experience with a modern engine underneath.
Because it is engine-based, its user agent is shaped by that engine. It is an uncommon browser, so expect very low volumes, all of which represent genuine human visitors.
How it identifies itself
Otter Browser may include an Otter product token in its user agent, alongside tokens from the underlying engine. We do not assert a fixed, version-stable string here, because the engine basis and tokens can vary between builds.
Where you see an Otter token, treat it as a niche-browser signal. As with any browser, the user agent is client-supplied and editable, so use it for attribution rather than authentication.
- Open-source browser recreating classic Opera's interface
- User agent shaped by its underlying web engine
- Very low volume; legitimate human traffic
How it appears in analytics and logs
A user agent referencing Otter Browser reflects its web engine and indicates a real human using a niche desktop browser, typically in very low volumes.
Diagnostic use case
Recognise the niche Otter Browser as human traffic and understand that its user agent follows its underlying engine rather than a mainstream brand identity.
What WebmasterID can help detect
WebmasterID classifies Otter Browser traffic as human browser activity where its token appears, avoiding mislabelling an uncommon browser as automation.
Common mistakes
- Classifying a rare Otter Browser hit as a bot by default.
- Assuming a fixed, version-stable Otter user-agent string.
- Confusing modern Otter Browser with the classic Opera it emulates.
Privacy and accuracy notes
An Otter token names a niche browser, not a person. WebmasterID treats it as a coarse browser-family signal and never as an individual identifier.
Related pages
- Midori and Falkon user agents
Midori and Falkon are lightweight, open-source desktop browsers popular in minimal Linux environments. Their user agents follow the engine each is built on at a given time, so they can look Chromium-like or WebKit-like rather than carrying a unique, headline brand token. That makes them low-volume but legitimate human browser traffic.
- Opera user agent
Opera switched to the Chromium engine, so its user agent resembles Chrome's but adds an OPR/ product token at the end. That OPR/ marker is how you tell Opera apart from Chrome and Edge in logs. This page covers the pattern and the historical Presto-era caveat.
- Browser user agents: how to read them
A browser user-agent string packs several tokens into one line: a legacy Mozilla prefix, a rendering-engine signature, the platform, and the browser itself. This page explains each part so you can read a UA without over-reading it, because the contents are client-controlled and can be copied by any client.
- Privacy-first analytics
Attribute niche browsers like Otter without tracking individuals.
Sources and verification notes
- Otter Browser — project siteOfficial site; open-source browser recreating classic Opera's interface. Exact version-stable UA not asserted.
Last reviewed 2026-06-24. Facts are checked against primary/official sources where available; uncertain specifics are marked “Data not yet verified” rather than guessed.