Prompt Template Builder
Fill a prompt template from spreadsheet rows and get one prompt per row.
Split a dataset into training, validation and test files with a repeatable shuffle.
Or drop a file — it is split in your browser, never uploaded
Test gets whatever is left. The same seed always produces the same split.
The Dataset Splitter divides JSONL, CSV or text data into training, validation and test files with a seeded shuffle, so the split is repeatable, removes duplicates first and repeats CSV headers in every file.
Before training or evaluating a model you need data it has never seen: a validation set to tune against and a test set to report on. Splitting by hand invites the classic mistakes — the file was sorted, so validation looks nothing like training, or duplicates land on both sides and inflate every score.
Paste or drop a JSONL, CSV or plain text file with one example per line, choose the percentages, and get three files. The rows are shuffled with a seeded generator, so the same seed always produces exactly the same split — which matters when you rerun an experiment and need the test set to stay put. Exact duplicates can be removed before splitting, and a CSV header line can be repeated at the top of every file.
Rounding never drops rows: whatever is left over goes to training, so the three parts always add back up to your total. Each part can be previewed, copied or downloaded with its original file extension.
The same seed always produces the same split, so test sets stay stable across runs.
The remainder goes to training, so the three parts always add up to the total.
Exact duplicates are removed first, so no example sits on both sides of the split.
The header line is repeated at the top of each output file.
80/10/10, 70/15/15, 90/10/0 and 80/20/0 in one click.
Paste one example per line, or drop a .jsonl, .csv or .txt file.
Set train and validation; test gets the remainder. Presets cover common splits.
Keep the same seed to reproduce the split exactly later.
Each part downloads separately, named after your original file.
80/10/10 is the common default. With small datasets, 70/15/15 gives evaluation sets large enough to mean something; with very large datasets, a smaller share such as 98/1/1 is often enough.
Files are often ordered by date, source or label. Without shuffling, the validation and test sets represent a different slice of the data than the training set.
It fixes the random shuffle, so the same seed and the same file always produce the same three parts. That keeps a test set stable across experiments.
If the same example appears in both training and test, the model is tested on something it memorised, and the score overstates real performance.
No. The split happens in your browser and files are created on your device.
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