You’re looking at the closest head-to-head in our EDC comparison series. Both Castor and Viedoc are cloud-native SaaS platforms. They offer transparent per-study pricing and share strong reputations for user experience.
The real differences come down to native randomization and native trial supply management. You also need to weigh the depth of EU MDR/PMCF support, the 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 | Native (via Viedoc eSignature) |
| Randomization | Native (variable-block, stratified) | Native (incl. trial supply) |
| RWE / Registry | Mature, native support | Supported (registries, observational, PMS) |
| EU MDR / PMCF | Deep support | Growing support |
| Pricing model | Per-study, transparent | Per-study, transparent |
| Implementation speed | Fast (weeks) | Fast (weeks) |
| Primary markets | Global (160+ countries) | Global (75+ countries) |
| Feature | Castor | Viedoc | Advantage |
|---|---|---|---|
| Cloud-native SaaS | Yes | Yes | Both strong |
| No-code study builder | Yes | Yes | Both strong |
| eCOA breadth | Native ePRO, eClinRO, eObsRO. 95%+ ePRO compliance | Viedoc Me (ePRO-focused) | Castor |
| Patient app with BYOD support | Yes | Yes (Viedoc Me) | Both strong |
| Native eConsent | Yes | Yes (integrated in Viedoc Me) | Both strong |
| Native randomization | Yes (variable-block, stratified) | Yes | Both strong |
| RWE / Registry support | Mature, native. 6,400+ RWE and registry studies, a registry live 10+ years | Supported | Castor |
| EU MDR / PMCF support | Deep support. 220+ PMCF studies | Growing support | 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 | 160+ countries, truly global | 75+ countries, 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 160+ countries, Castor stands out for its native integration of EDC, eCOA (including eClinRO and eObsRO beyond just patient-reported outcomes), eConsent, native randomization, 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 UX and strong 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.
Both Castor and Viedoc are strong and capable modern platforms for many Phase I, II, and III studies. Castor is the stronger fit when your program requires randomization-integrated EDC, EU MDR or PMCF, RWE and registries, or multi-modal eCOA. Otherwise, your choice often comes down to UI preference, existing relationships, regional support, and team familiarity.
Both platforms 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. You can then let your team’s interaction with the interface and the vendor’s understanding of your requirements guide your final decision.
Castor capabilities come from our product documentation, the Pollux capability verification (25 September 2026), and the Castor Marketing Claims Register. We verified Viedoc capabilities against their own pages, fetched on 25 September 2026.
Castor is better for studies requiring native randomization, 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.
Both include native randomization. Viedoc also offers native trial supply management (Viedoc Logistics) as part of its RTSM. Castor provides native variable-block and stratified randomization, and connects specialized RTSM/IRT partners through open REST APIs for complex drug supply and kit logistics.
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.
Yes. Both operate on transparent per-study pricing models. Pricing is typically based on study duration, number of sites, and number of enrolled subjects. Contact each vendor for a detailed estimate tailored to your trial.