jsonl-viewer: Viewing and Editing Fine-Tuning Datasets in JSONL
Melvin Vivas · X post · 2026-08-31 · Open on X
Topics: Fine-tuning & Model Customization, AI Dev Tools & Productivity · Level: beginner
Summary
The creator built jsonl-viewer, an open-source tool for viewing and editing .jsonl (JSON Lines) files. Fine-tuning and training datasets are usually stored in this format. He asks users to try it and request features.
Key points
- Fine-tuning and training datasets are usually stored as JSON Lines (.jsonl), with one JSON object per line
- jsonl-viewer lets you view and edit .jsonl files so dataset curation is easier
- It is open source on GitHub (donvito/jsonl-viewer), and the creator welcomes feature requests
Resources mentioned
- donvito/jsonl-viewer · repo · github.com · free
Open-source tool for viewing and editing .jsonl files (fine-tuning datasets) and agent traces from Codex, Claude Code, Pi and Hermes.
Also in: jsonl-viewer: Live Traces for Codex Orchestrator and Subagents (Melvin Vivas on X · notes), See live Codex traces with the jsonl-viewer tool (Melvin Vivas on X · notes), Melvin Vivas's open-source AI tools, built with Codex (Melvin Vivas on X · notes), Analyzing Codex Traces with jsonl-viewer (Melvin Vivas on X · notes) and 12 more
Try this
- Try jsonl-viewer on your fine-tuning datasets and tell the creator which features you need
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