Both are cloud EDC platforms aimed at teams that want to build studies themselves, so the differences sit in module scope, support model and fit. This page gives you the questions that separate them and a third option to test the same way.
Free sandbox · No credit card · 21 CFR Part 11 aligned
| Medrio | Castor | Capture | |
|---|---|---|---|
| ePRO and eConsent in the same study | Ask vendor | Ask vendor | Yes, one audit trail |
| Study build by your own team | Ask vendor | Ask vendor | Yes, AI-drafted |
| Amendment turnaround and cost | Ask vendor | Ask vendor | Edit and re-approve forms |
| Hands-on trial before contract | Ask vendor | Ask vendor | Free sandbox |
| Priced in writing for your scenario | Request quote | Request quote | Pricing page |
The short version
Positioning
Both vendors are usually evaluated by teams that do not want an enterprise services-led build. Medrio is commonly associated with early-phase and small-to-mid-size sponsors and CROs, while Castor is associated with academic groups, mid-size sponsors and decentralised or device-study workflows. Aggregator sites mark these descriptions as low-to-moderate confidence, so use them to draft questions.
What the descriptions cannot tell you is how either behaves on your protocol: how patient-reported data is collected, how consent is captured and tied to the study record, how amendments are handled and where the support line ends. The table below turns those into questions.
Existing Capture pages cover each vendor separately: Capture vs Medrio, Capture vs Castor, Medrio alternatives and Castor EDC alternatives.
Evaluation
Send the same list to every vendor and keep the answers in writing.
| Topic | Question | What Capture offers for comparison |
|---|---|---|
| Participant data | Are questionnaires and consent in the same study and audit trail as site data, or separate modules? | EDC, ePRO and eConsent share one study and one audit trail. |
| Build | How much can our team build without vendor services, and who is accountable for the build? | You build it. The AI study builder drafts visits and forms from a protocol upload; nothing saves without human review. |
| Amendments | What happens when the protocol changes after go-live, and is it billed? | Forms move from draft to approved; approved forms are locked for live use. Edit in draft, preview, approve. |
| Randomization | Is randomization native, or a separate system? | Configurable randomization in the same platform; allocation is logged. Check any IRT needs separately. |
| Data cleaning | How are edit checks and queries configured? | Edit checks raise auto-queries when a value breaks a rule; SDV is set per field. |
| Exports | What do we receive at lock and at exit? | CSV/Excel with an automatic data dictionary, audit trail export, and SDTM as SAS XPT with Define-XML. |
| Support | What support hours and channels apply, and what is included? | Email support, typically under 24-hour response; documentation and video tutorials. Ask both vendors for their terms. |
| Total cost | What are all charges over 24 months for our enrolment? | Core from $1,000/month with one live study plus $50 per participant per month; see the pricing page for current terms. |
Capture rows are from the Capture pricing page and product pages. Vendor columns are deliberately blank: ask Medrio and Castor directly.
Upload your protocol to the free sandbox, review the AI draft, and time how long a testable study takes. No card, no time limit.
Hands-on test
Both vendors are known for quick builds, so make the test hard enough to separate them: one visit with a lab table, a repeating concomitant medication row and a participant diary. Ask each vendor to build it and count days and questions. This is a demo-data example of a concomitant medication form in Capture.
Medication
CMTRTStart date
CMSTDTCEnd date
CMENDTCBefore start date: query raised
Cost shape
Even without published prices you can compare how cost is structured. Ask each vendor whether charges scale by study, site, participant or module, whether ePRO and eConsent are separate line items, whether amendments or extra environments are billed, and what exit and data export cost. Castor's own page describes per-study pricing; confirm what that means for your scenario in a quote, not a web page.
See EDC software pricing guide and EDC per-patient pricing explained, and model your enrolment with the EDC cost calculator.
Decision aid
Test Medrio and a lean option on the same visit.
Ask both vendors how participant-facing modules and device data are handled.
Get quotes from both and compare with a free-sandbox option such as Capture; see the academia page.
Ask for amendment turnaround and cost from all three.
Check site count, support hours and validation documents, then test Capture's Phase 3 controls.
Process
Same enrolment, sites, modules and two amendments to Medrio, Castor and your third option.
Include a lab table, a repeating row and a diary; count people and days.
Compare answers on consent, exports, support and 24-month cost.
Switching
See how to migrate from Medrio, how to migrate from Castor and how to switch EDC vendors mid-study. Related pairings: Castor vs Medidata Rave and REDCap vs Castor.
Neither wins in general. Both are cloud EDC platforms for teams that build their own studies. The better fit depends on your participant-facing modules, support needs and amendment frequency. Test both with the same visit.
We do not quote either vendor's pricing because we cannot verify it. Ask both to price the same enrolment, sites and modules and compare the 24-month total.
Castor describes integrated eCOA and eConsent modules; third-party benchmarks describe Medrio as covering EDC, data management and ePRO. Confirm current modules and your instruments with each vendor.
They are a weak signal. Review counts differ a lot between products, reviewers are self-selected, and ratings do not reflect your protocol. Use them only to prompt questions.
Because the shortlist should include a self-serve option with a free sandbox. Capture combines EDC, ePRO, eConsent and randomization in one audit trail and publishes its pricing, so it is quick to test alongside the others.
Yes. Capture supports Phase 1 through Phase 3, including SDV per field, freeze and lock, blinded roles and multi-site filtering.
Send identical written questions to every vendor, build one real visit with a lab table and a repeating row in each, and compare people involved, elapsed time and 24-month cost.
Build the same visit in Capture, free. No credit card; you pay only at go-live.