jsonl-viewer: a tool to view and edit JSONL training datasets
Melvin Vivas · X post · 2026-09-06 · Open on X
Topics: Fine-tuning & Model Customization, AI Dev Tools & Productivity · Level: beginner
Summary
The creator shares his open-source jsonl-viewer, a tool for viewing and editing .jsonl files. These files are commonly used for fine-tuning and training datasets. It's useful for checking dataset records before training.
Key points
- JSONL (one JSON object per line) is the usual format for fine-tuning and training datasets.
- donvito/jsonl-viewer lets you view and edit .jsonl files.
- The creator later says it supports traces, which helps when monitoring agent runs.
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 own fine-tuning or trace JSONL files.
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