Split Klaviyo CSV Lists into Random Groups
Create Holdout Groups & A/B Test Segments Instantly
Free tool to split customer lists into 2-10 random groups with custom ratios. Perfect for email campaign testing, holdout analysis, and controlled experiments.
🔒 100% Privacy-Safe: All processing happens in your browser. Your data never leaves your device.
Upload Your CSV
Drag and drop your CSV file here, or
CSV files only
How It Works
Upload Your List
Drop your CSV file with email contacts from Klaviyo
Configure Your Split
Choose how many groups (2-10) and set your holdout percentage
Download Split Files
Get a ZIP file with all your segmented lists ready for upload
Example Split Preview:
Privacy First: All processing happens in your browser. No data is uploaded to any server.
Perfect for splitting email lists, customer data, or any CSV for A/B testing and campaigns.
How to Use the Klaviyo List Splitter
This tool helps you split CSV customer lists into random groups for A/B testing, holdout analysis, and controlled email campaigns. Unlike manual splitting, this ensures truly random distribution without bias.
Common Use Cases
- •A/B Campaign Testing: Split your list into 2-5 groups to test different subject lines, send times, offers, or creative approaches
- •Holdout Groups: Create a control group (10-30%) that doesn't receive campaigns, allowing you to measure incremental lift
- •Flow Testing: Split subscribers to test different automation flow sequences
- •Campaign Throttling: Split large lists into smaller batches to avoid sending spikes
- •Multi-Variant Testing: Test 3-10 different variations simultaneously with equal distribution
How Random Splitting Works
The tool uses the Fisher-Yates shuffle algorithm to ensure truly random distribution:
- 1. Shuffle: All rows are randomly reordered using cryptographically secure randomization
- 2. Calculate Ratios: If you set a 20% holdout with 3 groups, the tool calculates: Groups 1-3 get 26.7% each (80% ÷ 3), Holdout gets 20%
- 3. Split: The shuffled data is divided into groups based on calculated percentages
- 4. Package: All groups are packaged into a ZIP file with a summary for easy upload to Klaviyo
Best Practices for List Splitting
- ✓Start with 2-3 groups: Don't over-split your audience unless you have 50k+ subscribers
- ✓Use 10-30% holdouts: This provides statistically significant control groups without sacrificing too much reach
- ✓Track group names: Upload each group as a separate segment in Klaviyo with clear naming (e.g., "Campaign_Test_Group_A")
- ✓Maintain groups over time: Don't re-randomize mid-test - keep the same groups for campaign series
- ✓Measure incrementality: Compare holdout group behavior (purchases, engagement) vs. test groups to prove campaign impact
Why Privacy Matters
Unlike cloud-based CSV tools that upload your customer data to third-party servers, this tool processes everything locally in your browser using JavaScript. Your customer emails, names, and data never leave your computer. This ensures GDPR compliance and protects sensitive customer information.
Technical Details
- Supports CSV files up to 1M+ rows (limited only by browser memory)
- Handles all CSV formats exported from Klaviyo, Shopify, or other platforms
- Preserves all columns and data integrity during splitting
- Generates downloadable ZIP file with individual CSV files for each group
- Includes a summary.txt file showing row counts and percentages