This is the closest head-to-head in the EDC comparison series. Both Castor and Viedoc are cloud-native, mid-market SaaS platforms with transparent per-study pricing and strong reputations for user experience.
The real differences come down to native RTSM, depth of EU MDR/PMCF support, breadth of eCOA modules, and RWE/registry features. This guide gives you an honest, side-by-side look to guide your selection.
| Feature | Castor | Viedoc |
|---|---|---|
| Best for | Unified native stack; MDR/PMCF; eCOA breadth; RWE | Strong UX; Nordic/European presence; streamlined workflow |
| Headquarters | Amsterdam, Netherlands | Uppsala, Sweden |
| eCOA module | Native (ePRO, eClinRO, eObsRO) | Viedoc Me (primarily ePRO-focused) |
| eConsent | Native module | Embedded in Viedoc Me |
| RTSM (native) | Yes | No (third-party integration) |
| RWE / Registry | Mature, native support | Limited capabilities |
| EU MDR / PMCF | Deep support | Growing support |
| Pricing model | Per-study, transparent | Per-study, transparent |
| Implementation speed | Fast (weeks) | Fast (weeks) |
| Primary markets | Global (90+ countries) | Nordic/Scandinavia, expanding Europe and North America |
| Feature | Castor | Viedoc | Advantage |
|---|---|---|---|
| Cloud-native SaaS | Yes | Yes | Both strong |
| No-code study builder | Yes | Yes | Both strong |
| Native eCOA (ePRO + eClinRO + eObsRO) | Yes (all three) | Partial (ePRO only in Viedoc Me) | Castor |
| Patient app with BYOD support | Yes | Yes (Viedoc Me) | Both strong |
| Native eConsent | Yes | Yes (integrated in Viedoc Me) | Both strong |
| Native RTSM (randomization) | Yes | No (third-party required) | Castor |
| RWE / Registry support | Mature, native | Limited | Castor |
| EU MDR / PMCF support | Deep, mature | Growing but less mature | Castor |
| DCT / hybrid trial support | Yes | Yes | Both strong |
| UI/UX quality | Excellent | Excellent (strong reputation for elegance) | Comparable |
| Pricing transparency | Per-study, clear | Per-study, clear | Both strong |
| Global reach | 90+ countries, truly global | Nordic/Scand. strength, expanding globally | Castor |
| Academic / IIT support | Strong | Strong (esp. in Europe) | Comparable |
Castor is a unified, cloud-native clinical research platform built by researchers for researchers. Founded in Amsterdam and operating across 90+ countries, Castor stands out for its native integration of EDC, eCOA (including eClinRO and eObsRO beyond just patient-reported outcomes), eConsent, RTSM, and RWE/registry capabilities, all on a single platform without third-party dependency.
Viedoc is a Scandinavian-origin cloud EDC platform (Uppsala, Sweden) with a reputation for outstanding user experience and strong roots in academic research and CRO adoption, particularly across Europe. Viedoc is expanding globally and competing directly with Castor in mid-market SaaS-native EDC.
Use these criteria to self-select based on your study type, organization, and priorities.
For many Phase I, II, and III studies without randomization requirements, EU MDR programmes, or complex eCOA workflows, both Castor and Viedoc are strong, capable, modern platforms. The choice often comes down to personal preference for UI, existing relationships, regional support, and team familiarity.
Both offer per-study pricing, cloud-native architecture, and fast implementation. The most reliable way to decide is to request a hands-on demo of each platform tailored to your trial design, and let your team’s interaction with the interface and the vendor’s understanding of your requirements guide your final decision.
No simple answer. Castor is better for studies requiring native RTSM, EU MDR/PMCF support, multi-modal eCOA, or RWE/registry capabilities. Viedoc is better if your priority is UI/UX elegance, Nordic/European regional support, and streamlined ePRO workflows. For many trials, both are equally strong. Choose the one your team prefers after a demo.
Castor’s eCOA is broader: it includes patient-reported outcomes (ePRO), clinician-reported outcomes (eClinRO), and observer-reported outcomes (eObsRO). Viedoc Me is primarily ePRO-focused, with eConsent integrated. Both have strong patient UX. If you need eClinRO or eObsRO, Castor is the better fit.
Both are strong in Europe. Viedoc has deeper roots and stronger local presence in Scandinavia and the Nordic region. Castor has broader pan-European reach and stronger EU MDR/PMCF support for medical device trials. For most pharma trials in Europe, both are equally viable.