Castor vs REDCap:Which is more popular?
In September 2026, REDCap had more branded searches than Castor among clinical trial software worldwide. REDCap had about 18,100 branded searches, while Castor had 4,400. REDCap made up 4.2% of all clinical trial software searches we track, and Castor accounted for 1%. When we asked ChatGPT and Google AI Overviews about clinical trial software, Castor and REDCap each appeared in two of the five answers. Castor and REDCap were each mentioned first in one of the two answers that named either.
Who do people search for more?
REDCap, about 4 searches for every 1 for Castor
Who does AI mention more?
Both were mentioned in 2 of 5 answers.
Who does AI recommend more?
Each is named first in 1 of 2 answers.
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Top clinical trial software in ChatGPT and Google AI Overviews
In three ChatGPT questions and two Google AI Overviews, Castor and REDCap were each mentioned in two out of five: in two of the three ChatGPT answers, but not in either of the two Google AI Overviews. Castor and REDCap were each listed first in one of the two answers that named either.
Most recommended by AI
Brands get a higher ranking if they are mentioned earlier in the answers.
Mentioned by AI
Each dot is one answer, filled in when that answer mentions the brand.
Medidata5 of 5Named in 3 of 3 ChatGPT answersNamed in 2 of 2 Google answers
Veeva4 of 5Named in 2 of 3 ChatGPT answersNamed in 2 of 2 Google answers- REDCap2 of 5Named in 2 of 3 ChatGPT answersNamed in 0 of 2 Google answers
Castor2 of 5Named in 2 of 3 ChatGPT answersNamed in 0 of 2 Google answers
Oracle Health1 of 5Named in 1 of 3 ChatGPT answersNamed in 0 of 2 Google answers
IQVIA0 of 5Named in 0 of 3 ChatGPT answersNamed in 0 of 2 Google answers
Clario0 of 5Named in 0 of 3 ChatGPT answersNamed in 0 of 2 Google answers
See every answer about clinical trial software
5 answers
Asked ChatGPT
“Which clinical trial platform should I use?”
Asked ChatGPT
“What are the best clinical trial platforms?”
Asked ChatGPT
“What's the best clinical trial platform for a clinical research team?”
Searched Google, AI Overview
“clinical trial software”
Searched Google, AI Overview
“clinical research software”
Brands are shown in the order each answer named them. The survey took place in the United States on October 20, 2026.
Is Castor or REDCap more popular in search?
This chart shows how often people search Google for Castor and REDCap by name. Each line represents a brand's share of searches for all seven clinical trial software we track, month by month, from English-language searches worldwide.
Share of searches by month for REDCap, Castor. The figures are in the table below the chart.
View monthly share of searches table
| Month | IQVIA | Veeva | Clario | Medidata | REDCap | Oracle Health | Castor |
|---|---|---|---|---|---|---|---|
| Oct 2025 | 56.2% | 13.8% | 13.8% | 9.3% | 3.4% | 2.3% | 1.2% |
| Nov 2025 | 60.9% | 12.3% | 12.3% | 8.2% | 3% | 2% | 1.3% |
| Dec 2025 | 57.6% | 14.2% | 11.6% | 9.5% | 3.5% | 2.3% | 1.3% |
| Jan 2026 | 57.7% | 14.2% | 11.6% | 9.5% | 3.5% | 2.3% | 1.3% |
| Feb 2026 | 59% | 14.5% | 9.7% | 9.7% | 3.6% | 2.4% | 1.1% |
| Mar 2026 | 56.9% | 14% | 11.5% | 9.4% | 4.2% | 2.8% | 1.2% |
| Apr 2026 | 58.4% | 14.4% | 9.6% | 9.6% | 4.3% | 2.4% | 1.3% |
| May 2026 | 55.5% | 16.7% | 11.2% | 9.1% | 4.1% | 2.2% | 1.2% |
| Jun 2026 | 52% | 19.1% | 10.5% | 10.5% | 4.7% | 2.1% | 1.1% |
| Jul 2026 | 52% | 19.1% | 10.5% | 10.5% | 4.7% | 2.1% | 1.1% |
| Aug 2026 | 53.6% | 19.7% | 10.8% | 8.8% | 3.9% | 2.2% | 0.96% |
| Sep 2026 | 57% | 17.1% | 9.4% | 9.4% | 4.2% | 1.9% | 1% |
How has the Castor and REDCap comparison changed over the last 12 months?
3 findings
- REDCap was ahead of Castor in every measured month of the 12 months ending September 2026.
- Across the 12 months ending September 2026, Castor’s share of searches among clinical trial software worldwide moved from 1.2% to 1%, and its estimated monthly branded searches moved from 5.4K to 4.4K.
- Across the 12 months ending September 2026, REDCap’s share of searches among clinical trial software worldwide moved from 3.4% to 4.2%, and its estimated monthly branded searches moved from 14.8K to 18.1K.
How did search popularity change for clinical trial software worldwide in September 2026?
2 changes
How are branded searches counted?
2 search terms
Brandwave collects information about searches that people make online using Castor’s and REDCap’s names. When viewed over time, estimated search volumes for these branded terms can be used to understand whether interest in the brands is growing, holding steady, or fading.
Other head-to-heads among clinical trial software
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