RadarOpus and Similia compared

RadarOpus and Similia both give you a repertory, a Materia Medica library and somewhere to keep your cases. They are built differently: RadarOpus is a program installed on your computer, and Similia works in your browser. They also carry different books. This page sets out the cost of access, the content and the working terms of each, from what both companies publish.

Checked 27 October 2026. We sell RadarOpus in the UK, so read this as a reseller's comparison built from public information. It is not an independent test. Prices are shown in the currency each supplier displays and are not converted.

Who each suits

Cost of access over 1, 5 and 10 years

For the subscriptions, the method is the monthly price × 12 × the number of years, at today's rates, with no add-ons. It is an illustration rather than a forecast. For RadarOpus, the figure is the one-off package price. The libraries differ, so read each row as the cost of reaching that particular library.

Similia also offers annual billing, advertised as "1 month free", and three-year billing, charged as 30 months of the monthly price; at the displayed Base rate that is €509.70 every three years. The annual checkout total is not shown publicly. Similia says it sells Lifetime Pro in US dollars, euros and pounds, but only the dollar prices are displayed, and we could not confirm from its public pages whether its prices include VAT. Check the final amount at checkout.

RadarOpus can also be rented, through Zeus Soft, from €6 a month (Zeus Soft's prices exclude local tax). The Radar UK shop sells lifetime licences in one payment; see How to buy for instalments and rental.

What "lifetime" means on each side

• Similia Lifetime Pro lasts "for as long as Similia provides the service". It belongs to one named practitioner, cannot be transferred and ends on the holder's death. A work withdrawn by its publisher may be withdrawn for all users, Lifetime holders included. It comes with 1,000 AI credits once, with no monthly allowance; premium repertories are add-ons. There is no free trial on Lifetime, and a full refund is available if you ask within 14 days. If you stop paying instalments, access runs to the end of the paid month and the account moves to Free, with your data intact.
• A RadarOpus licence from the UK shop is bought once. Upgrades have been free so far: every major version from 3.0 to 4.2 was free for licence holders on 2.2.16 or later. The licence terms updated in August 2026 allow future upgrades to be charged, and support may be charged. A licence without a dongle can be moved to another computer a limited number of times, and a lost or damaged computer needs a purchased replacement key.

The libraries are different

No price table shows this, so ask first which books your course or practice relies on.

• RadarOpus: Core carries Kent, Boericke and Phatak, with no Synthesis. Essentials carries Synthesis Treasure Edition 2009. Advanced and Optimum carry Synthesis Adonis, with a wider set of repertories alongside it. The Materia Medica library runs from 21 volumes in Core to 982 in Optimum. See Synthesis in RadarOpus.
• Similia: the Free plan includes eight classical repertories (Kent, Boericke, BBCR, Hering's Guiding Symptoms, Boger's Synoptic Key, Ward and Roberts Sensations As If, and Bönninghausen's Therapeutic Pocket Book) and 21 classic Materia Medica books. Pro adds premium repertories: Murphy MetaRepertory, Complete Repertory 2026, Saine Repertory 2025 and Suggesta 2.1, with Q-Rep 5 as an add-on. Similia does not list Synthesis among its repertories.

How you work, and what works offline

• RadarOpus is installed on Windows 10 or 11, or on macOS 15 Sequoia or later, and runs natively on Mac. It needs the internet for the first activation, then for a licence check every 30 days, or every 12 months with a dongle. Between checks you work offline. On a phone or tablet, OpusGo is a separate app with its own yearly subscriptions. More on RadarOpus on Mac.
• Similia runs in the browser and can be installed as a web app on phones, tablets and computers (on Mac, Safari needs macOS Sonoma or later). Its offline mode is in beta and on paid plans only, not during the trial. You reconnect every 30 days, premium content is available on up to three devices, and features such as AI, search by meaning, dictation and deleting cases need a connection.

Where your patient files are kept

• RadarOpus stores patient files on your own computer, encrypted. Cases can only be opened through RadarOpus, and RadarOpus runs only with your licence. Password protection can be switched off from version 3.3, and backups are yours to keep.
• Similia stores data in the cloud, "encrypted in transit and at rest". Its data processing agreement (version 10 September 2026) states that it "is not an end-to-end encryption service" and that patient data is not used "to train or fine-tune AI models". It lists its subprocessors; no hosting country is named on its public pages.

Neither arrangement makes a practice compliant or non-compliant by itself: how you handle records still matters.

Trials, refunds and students

• RadarOpus: a 15-day free trial of the full program, and a 14-day refund on a permanent licence bought from Radar UK. College licences by enquiry.
• Similia: a 14-day free trial of Pro. Subscriptions can be cancelled at any time; we found no published refund terms for annual or three-year billing. Students are asked to contact Similia for special pricing.

If Synthesis and an installed program are what you are looking for, compare the four RadarOpus packages. For a wider view, our homeopathy software buyer's guide covers more products.