What JSON Lines is
JSON Lines is one complete JSON object per line, with no enclosing array and no commas between records. The file is not valid JSON as a whole, and that is the point.
Log pipelines, machine learning datasets and anything that appends records or reads them in a stream.
What Box-Drawing Table is
The same grid as an ASCII table, drawn with Unicode box-drawing characters instead of punctuation.
Terminal UIs and documentation where the output is known to be UTF-8.
What changes when you convert JSON Lines to Box-Drawing Table
Each line is parsed on its own, so a corrupt record does not take the file with it. Keys are unioned across lines in first-seen order, so a record missing a field leaves that cell empty rather than shifting the columns.
Prettier than plus signs, and safe anywhere the reader's font has the box-drawing block, which is almost everywhere in 2026.
What carries over from JSON Lines to Box-Drawing Table
JSON Lines records 4 things about a table that box-drawing table has no way to hold.
JSON Lines distinguishes a number from the text of a number; box-drawing table does not, so every value arrives as text and has to be re-parsed by whatever reads it next.
An empty cell and a missing one are the same thing in box-drawing table, so a null and an empty string in the JSON Lines both come out blank and can no longer be told apart.
JSON Lines can hold a value that is itself a list or an object. box-drawing table has only flat cells, so nested values are flattened into one cell rather than being spread across columns.
box-drawing table marks header cells differently from data cells, so the keys are lifted out and written once as a marked header row rather than repeated on every row.
JSON Lines can be read one record at a time. box-drawing table has to be complete before it means anything, so the whole table is held in memory while it is written and a file that gets cut off part way through is not partly usable - it is unusable.
The identifier 007 comes out of the Box-Drawing Table as 007. Reading it as a number would have made it 7, and an id that changes value is worse than one that stays text.
The role "Analyst, data" survives with its comma, in one cell rather than split across two. That is the first thing to check in any converted table, and the usual place a Box-Drawing Table file goes wrong.
The quotes around Jonah "Jo" Pryce are left as a plain quote character in the Box-Drawing Table.