The most used feature flag and A/B testing tools
We track 25 feature flag and A/B testing tools. The most used is VWO, found at 8,701 companies as of October 2026, ahead of Optimizely (6,891) and LaunchDarkly (4,827).
Two groups share this category. Feature-flag and experimentation platforms (LaunchDarkly, Statsig, GrowthBook, ConfigCat) let engineering teams release features gradually and measure their effect. Website testing and personalization tools (Optimizely, VWO, AB Tasty, Kameleoon, Mutiny, Dynamic Yield) let marketing teams change pages for different visitors without a deploy.
Feature flag and A/B testing tools ranked by companies using them
“Share” is each tool's part of all 39,243 matches in this category; a company that uses two tools counts for both.
| # | Tool | Companies | Share | Last 30 days | Most popular with |
|---|---|---|---|---|---|
| 1 | 8,701 | 22% | +2−1 | 1,001–5,000 employees (2.7×) | |
| 2 | 6,891 | 18% | +5−2 | Automotive (13×) | |
| 3 | 4,827 | 12% | +1 | Automotive (21×) | |
| 4 | 2,294 | 5.8% | +1−1 | Apparel & Fashion (5.8×) | |
| 5 | 2,233 | 5.7% | – | Higher Education (2.9×) | |
| 6 | 1,733 | 4.4% | – | Automotive (20×) | |
| 7 | 1,583 | 4.0% | +1 | Software (4.0×) | |
| 8 | 1,566 | 4.0% | +1 | Apparel & Fashion (6.7×) | |
| 9 | 1,422 | 3.6% | +1 | 5,001–10,000 employees (6.3×) | |
| 10 | 1,303 | 3.3% | +1 | 10,000+ employees (14×) | |
| 11 | 1,197 | 3.1% | – | Cosmetics (22×) | |
| 12 | 855 | 2.2% | – | 10,000+ employees (11×) | |
| 13 | 612 | 1.6% | – | Veterinary (168×) | |
| 14 | 589 | 1.5% | – | Cosmetics (30×) | |
| 15 | 575 | 1.5% | +1 | 10,000+ employees (17×) | |
| 16 | 505 | 1.3% | – | 1,001–5,000 employees (3.7×) | |
| 17 | 465 | 1.2% | +1 | Apparel & Fashion (28×) | |
| 18 | 353 | 0.90% | – | Software (2.2×) | |
| 19 | 313 | 0.80% | +2 | Hospitality (6.5×) | |
| 20 | 306 | 0.78% | – | 51–200 employees (1.7×) | |
| 21 | 256 | 0.65% | +1 | Retail (3.9×) | |
| 22 | 218 | 0.56% | – | Software (5.7×) | |
| 23 | 174 | 0.44% | – | – | |
| 24 | 168 | 0.43% | +1 | Software (5.5×) | |
| 25 | 104 | 0.27% | −1 | Software (7.4×) |
“Most popular with” is the industry or company size where the tool is most over-represented compared with all companies we've scanned. Starts and stops compare two scans done the same way.
Who's gaining and losing customers
- Optimizely: 5 started, 2 stopped in the last 30 days
- Statsig: 2 started in the last 30 days
- VWO: 2 started, 1 stopped in the last 30 days
- LaunchDarkly: 1 started in the last 30 days
- Intellimize: 1 started in the last 30 days
- GrowthBook: 1 started in the last 30 days
How to compare feature flag and A/B testing tools
- Who runs the tests: engineers in code, or marketers in a visual editor.
- Statistics engine and how results are reported.
- Performance: client-side testing scripts can cause page flicker.
- Pricing by monthly users, events or seats.
How we find feature flag and A/B testing tools
These tools load an SDK or snippet in the browser and call the vendor's API, so we find them in page scripts, tag managers and content security policies.
Every company on a tool's page links to the record behind the match. DNS is rechecked weekly and websites monthly, so tools a company stops using drop off the list.
Flags & Experiments FAQ
What are the most popular feature flag and A/B testing tools?
As of October 2026, the most popular feature flag and A/B testing tools by number of companies using them are VWO (8,701 companies), Optimizely (6,891 companies) and LaunchDarkly (4,827 companies), according to runsonwhat. VWO alone accounts for 22% of the 39,243 Flags & Experiments matches runsonwhat has, and the top three together for 52%. 25 feature flag and A/B testing tools have at least one confirmed customer.
VWO vs Optimizely: which is more popular?
VWO is more popular: 8,701 companies show public evidence of VWO, against 6,891 for Optimizely (1.3× as many), according to runsonwhat (October 2026). Among companies with more than 1,000 employees, though, Optimizely leads: 847 against 705. LaunchDarkly is third with 4,827.
Which feature flag and A/B testing tools do small businesses use most?
Among companies with up to 50 employees, the most used feature flag and A/B testing tools are LaunchDarkly (2,473 companies), VWO (2,197 companies) and Optimizely (1,984 companies), according to runsonwhat (October 2026). That differs from the overall ranking, where VWO leads. The counts cover companies with a known headcount; see each tool's page for the full size breakdown.
Which feature flag and A/B testing tools do large companies use most?
Among companies with more than 1,000 employees, the most used feature flag and A/B testing tools are Optimizely (847 companies), VWO (705 companies) and Adobe Target (312 companies), according to runsonwhat (October 2026). That differs from the overall ranking, where VWO leads. Large companies often run more than one tool in a category, so the same company can count for several.
Which feature flag and A/B testing tools are most popular in the United States?
In the United States, the most used feature flag and A/B testing tools are LaunchDarkly (3,582 companies), Optimizely (3,324 companies) and VWO (2,960 companies), based on companies runsonwhat has located there (October 2026). LaunchDarkly has 23% of the Flags & Experiments matches among companies based in the United States.
Which feature flag and A/B testing tools are most popular in the United Kingdom?
In the United Kingdom, the most used feature flag and A/B testing tools are VWO (681 companies), Optimizely (320 companies) and Convert (215 companies), based on companies runsonwhat has located there (October 2026). VWO has 31% of the Flags & Experiments matches among companies based in the United Kingdom.
Which feature flag and A/B testing tools do retail companies use?
Retail is the industry with the most Flags & Experiments matches, and its companies use LaunchDarkly (855 companies), Optimizely (678 companies) and VWO (447 companies) most, according to runsonwhat (October 2026). Each tool's page breaks its customers down by industry, so you can check where a tool over-indexes.
Which feature flag and A/B testing tools are companies adopting right now?
In the 30 days to October 2026, the most new adoptions runsonwhat recorded were for Optimizely (5 companies), VWO (2 companies) and Statsig (2 companies). A start is counted when a recheck finds a tool that the previous check of the same company, done the same way, did not.
How does runsonwhat rank feature flag and A/B testing tools?
runsonwhat counts the companies where a public record shows each tool in use and ranks by that count. These tools load an SDK or snippet in the browser and call the vendor's API, so we find them in page scripts, tag managers and content security policies. A company counts only when a direct record backs it up. The full method is at https://www.runsonwhat.com/methodology.