RadarOpus vs Similia — a head-to-head review

A working homeopath choosing between RadarOpus and Similia has typically narrowed the shortlist to two products and wants the side-by-side before committing to a lifetime licence or starting a Pro trial. The two are not built for the same buyer. RadarOpus is a desktop suite descended from the RADAR / Synthesis project, sold as a one-time lifetime licence (with a paid rental path as an alternative); Similia is a web-based subscription product with a permanent Free tier and four Pro editions.

The verdict is reader-type-dependent. For a practitioner whose case-taking is anchored in the Synthesis repertory and who values owning software outright rather than renting access, RadarOpus is the stronger product and the migration case for Similia is weakest — Synthesis is a RadarOpus exclusive on the desktop, and a lifetime licence with no recurring fee is a real advantage for a long-career practitioner. For a new practitioner, a student on a budget, a clinic that wants multi-device web access, an iPad- or Linux-first practitioner, or anyone who wants real AI-assisted case-taking inside the software, Similia ranks first; start on its Free tier and elect the 14-day Pro trial before committing.

At a glance

RadarOpus owns repertory coverage because Synthesis is a desktop exclusive and is bundled, not rented per month. The AI dimension splits rather than collapses: both products ship an AI offering, but they are different things — RadarOpus's is a free external ChatGPT companion that explicitly refuses to solve cases, while Similia's is an in-app, credit-metered set of case-taking tools. Platform breadth, the entry-price gradient, and web/multi-device access favour Similia for new practitioners, students, and clinics; the lifetime-ownership economics and the Synthesis bundle favour RadarOpus for an established Synthesis-trained practitioner.

What RadarOpus is

RadarOpus is the desktop flagship from Zeus Soft and the descendant of the RADAR project, first developed at the University of Namur (Belgium) under Jean Fichefet; Frederik Schroyens outlined a request for collaboration in 1986, and Synthesis has been used as the database for RADAR since 1987. The Synthesis repertory is based on the 6th American edition of Kent's repertory and retains its rubrics, remedies, and philosophical background. The desktop suite bundles Synthesis, a case manager, a materia-medica library, a powerful search tool, and more than 80 repertories including Boenninghausen, Boger, Kent and Murphy. Modern provings by Sankaran are included within Synthesis itself, and Scholten's Periodic Table Map is available as a separate module for Element Theory analysis of the minerals.

Commercially, RadarOpus is sold as a one-time lifetime licence — "When you purchase RadarOpus, you are purchasing a lifetime license, so it's a one-time charge" — with a paid rental path for practitioners who prefer time-limited access with support and updates. There is no permanent free tier for the desktop program; the sole no-cost path is a time-limited demo, advertised as a 30-day free trial on the US mirror and a 14-day trial on the UK mirror, requiring name and email only. Buy-now lifetime prices on the global radaropus.com store sit behind a free-account login. A student-discount path exists, including a "Pathway to Ownership Program," though the vendor does not publish a specific rate.

RadarOpus runs natively on Windows and macOS, with a .exe installer for Windows 10/11 (64-bit) and a .dmg installer for Mac. No Linux client is listed in any official requirements or download page. There is no native iPad or Android client within RadarOpus itself; Zeus Soft addresses mobile through a separate product, OpusGo, a native iOS and Android app that is a distinct purchase from the desktop suite. OpusGo has its own permanent free tier — Kent's Repertory & Philosophy, Boericke's Pocket Manual, and Hahnemann's Organon — with paid bundles and add-ons on top, and the vendor markets it as the sole app to bundle Synthesis.

What Similia is

Similia is a web-based homeopathic-practice product with a permanent Free tier and four Pro editions. The Free tier covers the classic repertory, the classic materia-medica library, Semantic Search, and up to three new cases and three new analyses per month; it is usable indefinitely. The four Pro editions unlock the AI features, unlimited cases, the full case-management depth, and a matching premium repertory: Pro Base (USD 19.99/mo, 219.99/yr), Pro Murphy (USD 29.99/mo, 329.99/yr — Murphy's MetaRepertory and Nature's Materia Medica 4th ed.), Pro Complete (USD 29.99/mo, 329.99/yr — Complete Repertory 2026), and Pro Saine (USD 26.99/mo, 296.99/yr — Saine Repertory 2025). All four Pro plans are priced in USD, EUR, GBP, and INR, with annual variants. The product runs in any modern browser with no install; on mobile the path is an "Add to Home Screen" PWA shortcut rather than a native app-store app, which is the key delivery contrast with RadarOpus and OpusGo.

The AI surface is the largest single in-app differential. Semantic Search ships on the Free tier; the higher-effort AI tools sit behind Pro and an AI-credits budget of 100 credits per renewal (Student Complete is granted 1,000 initial credits). The canonical tools are AI-powered Photo & Notes (Photos to Rubrics, Notes to Rubrics, Upload Notes OCR), Live Mode (typed notes auto-added as rubrics), Live Audio Mode (Beta) (records and transcribes a consultation, extracts symptoms, and auto-adds rubrics — the audio is not saved, only the transcript and AI summary), and Case Timeline (AI timeline extraction). The interactive Periodic Table is a Pro feature for exploring mineral remedies by series, stages, themes, and remedy relationships.

On data and security, Similia documents in-app data export and an account-deletion flow (Settings → Danger Zone removes account data server-side, subject to legal-retention requirements), and states a HIPAA-ready / GDPR-compliant posture with TLS 1.3, AES-256, and BAAs with its AI processors. RadarOpus, by contrast, keeps the case database local on the practitioner's machine with export to RTF / PDF / Word — a different trade-off that some clinics will prefer outright.

Feature-by-feature

The two AI offerings are not the same category of thing, and neither strictly dominates. RadarOpus ships a free, external "Homeopathic Practice Partner" built on ChatGPT and heavily trained on classical homeopathy, whose stated uses are extracting rubric ideas from patient notes and offering an alternative perspective on remedy suggestions — but it is explicitly not a prescriber or shortcut and should not be used to solve cases, and the public link resolves to a custom GPT on chatgpt.com rather than to an in-app module. Similia's AI is the opposite trade-off: it lives inside the application as a metered, workflow-integrated set of tools (Photo & Notes, Live Mode, Live Audio Mode, Case Timeline) that act directly on the case the practitioner is taking. A practitioner who wants a free reflective sounding-board outside the case file is better served by RadarOpus's approach; a practitioner who wants AI to do work inside the consultation — turn a photographed note or a recorded interview into rubrics — is better served by Similia's.

How each one fits the workflow

A practitioner whose case-taking is anchored in Synthesis rubrics reads better on RadarOpus than on Similia, because Synthesis is bundled and the rubric numbering matches the printed Synthesis the practitioner trained on, and because Synthesis is a desktop exclusive that Similia does not ship. For this reader the lifetime-licence economics also favour RadarOpus: a one-time charge with no recurring fee is a durable advantage over a subscription for someone who expects a long career and already owns the bundle. The pragmatic move is to stay on RadarOpus, optionally evaluate Similia's Free tier as a companion for Semantic Search on ambiguous phrasing, and revisit only if a multi-device or AI-in-case workflow becomes a priority.

Several other profiles flip the picture. New practitioners and students benefit from the permanent Free tier and the fully published price list, where RadarOpus offers only a time-limited demo and login-gated buy prices. Clinics that want web access from any machine benefit from Similia's browser delivery; RadarOpus is a native desktop install per machine, with mobile served only by the separate OpusGo app. Linux-first practitioners are not served by RadarOpus at all, which lists no Linux client, whereas Similia runs in any modern browser. And practitioners who want AI to act inside the case — turning a photo of handwritten notes, typed notes, or a recorded interview into rubrics — will find that RadarOpus's AI companion deliberately does not do that, while Similia's Pro tools do.

Three things RadarOpus does not lack are worth naming precisely. RadarOpus does publish pricing (rental and US-mirror lifetime prices are public; global buy prices sit behind a free login); Zeus Soft does ship a native iOS and Android client, namely OpusGo, just not inside RadarOpus itself; and RadarOpus does have an AI offering, the ChatGPT-based Homeopathic Practice Partner. The genuine RadarOpus limitations against Similia are narrower and verifiable: no in-app AI case-taking, no Linux desktop, a native-install (not web) delivery model, and no permanent free tier for the desktop program.

Reader-type recommendation

Verdict

For a Synthesis-trained practitioner who wants to own software outright, or who wants a free AI sounding-board rather than AI inside the case file, RadarOpus is the better tool — Synthesis is its exclusive, the licence is a one-time lifetime charge, and the case database stays local. For a new practitioner, a student, a Linux- or web-first user, a clinic that wants multi-device access, or anyone who wants AI to turn notes, photos, or audio into rubrics during the consultation, Similia is the better fit, and the next step is the 14-day Pro trial.

References

Zeus Soft (2026) RadarOpus — Buy or Rent, https://www.radaropus.com/buy-or-rent/info.

Similia (2026) Knowledge base — Pricing and Subscription FAQ, AI credits, AI processing, Live Audio Mode, Interactive Periodic Table, Getting started, Managing Cases and Follow-ups, Security and privacy, https://similia.crisp.help/.

RadarOpus US (2026) Packages and 30-Day Free Trial, https://www.radaropus.us/packages/ and https://www.radaropus.us/30-day-free-trial-of-radaropus/. UK mirror 14-day trial: https://www.radar-uk.co.uk/.

RadarOpus UK (2026) Synthesis, https://www.radar-uk.co.uk/product/synthesis/. Murphy's Homeopathic Clinical Repertory 3rd ed. desktop add-on: https://www.radaropus.us/product/murphy-robin-homeopathic-clinical-repertory-3e/.

RadarOpus UK (2026) Software, https://www.radar-uk.co.uk/software/.

homeobook.com (2024) History and Development of the Synthesis Repertory, https://www.homeobook.com/history-and-development-of-synthesis-repertory/. Sankaran provings within Synthesis: https://www.radaropus.com/products/radaropus/content/repertories/frederik-schroyens-synthesis-treasure-edition.

Zeus Soft (2026) Scholten Periodic Table Map & Materia Medica module, https://www.radar-uk.co.uk/product/periodic-table-map/ and https://www.radaropus.us/product/scholten-jan-periodic-table/.

Zeus Soft (2026) RadarOpus Homeopathic Practice Partner (AI), https://ai.zeus-soft.com/ and https://chatgpt.com/g/g-68b6bda11df48191a0df61a2078ef2ae-radaropus-homeopathic-practice-partner.

Zeus Soft (2026) RadarOpus download / system requirements, https://www.radaropus.com/support/download and https://www.radar-uk.co.uk/software/. Helpdesk: https://helpdesk.zeus-soft.com/.

Zeus Soft (2026) OpusGo mobile app, https://opusgo.app/, https://apps.apple.com/us/app/opusgo/id6741098026, and https://play.google.com/store/apps/details?id=en.zeus.opusgo.

RadarOpus US (2026) Schools and student discounts, https://www.radaropus.us/schools/.