Definition
Plain language
A file format that stores one structured record per line, used for logs and datasets.
As stated in the literature
JSON Lines — a newline-delimited format where each line is an independent JSON object, common for streaming logs and training data; the format agentic IDEs use for local session histories parsed by ADR.
Why it matters: Its one-record-per-line layout makes large logs and datasets easy to stream and process piece by piece.
For example, a chat log might store each message as its own line, so a program can read them one at a time without loading the whole file.
Heard on the show
“They store them in SQLite databases and JSONL files in the user's home directory.”Episode 057 — How Uber Caught 206 Leaked Credentials With an LLM-Powered Security Stack