Random Assignment Generator
Create reproducible group assignments for A/B tests, control-treatment studies, multi-condition experiments, or batch allocation. Participants are shuffled and distributed round-robin across groups.
Also known as: group assignment · randomization · test groups
seeded
Output
About this tool, tips & examples
What it does
The Random Assignment Generator allocates participants to groups the way experiments demand: shuffled with a seed, then distributed round-robin so group sizes stay balanced. Choose a scheme — simple A/B, control vs treatment, or custom multi-group up to 20 conditions — and get an assignment you can reproduce and defend.
Common use cases
- A/B tests — split users, sessions, or URLs into balanced variants with a documented, reproducible allocation.
- Studies and trials — control/treatment assignment where “random and auditable” is a methodological requirement, not a nicety.
- Classroom experiments — assign students to conditions fairly and show them the mechanism.
- Load distribution — spread items across workers, batches, or reviewers evenly at random.
Settings
- Participants — one per line; blank lines ignored.
- Assignment scheme — A/B, control-treatment, or custom multi-group.
- Number of groups — 2 to 20 for custom schemes.
- Seed — the same seed and list always reproduce the identical assignment — record it in your methods notes.
Privacy note
Assignment happens locally in your browser — the participant list is never uploaded. The randomization is seeded and transparent; for regulated clinical work, follow your protocol’s dedicated randomization requirements.
FAQ
Why round-robin after shuffling? Shuffling supplies the randomness; round-robin distribution guarantees balance (group sizes within one). Pure random assignment can produce lopsided groups by chance — this construction can’t.
How do I document the randomization? Save the seed, scheme, and participant list. Anyone can re-run the assignment and get identical groups — reviewers appreciate that sentence.
Assignment vs picking vs splitting? This tool assigns everyone to labeled conditions; Random Picker selects a few winners; Group Splitter makes unlabeled teams. Same randomness, different shapes.