Want to import data from JSON Lines (JSONL / NDJSON / LDJSON) file to PostgreSQL ?
Try Withdata FileToDB, a desktop JSONL to PostgreSQL converter for Windows, MacOS, and Linux, Import JSON Lines to PostgreSQL, Easy and Fast.
- Can run in GUI mode, Step by Step, just a few mouse clicks.
- Can run in Command line, for Scheduled Tasks and Streams.
- Convert locally and privately, avoid uploading large or private JSONL file(s) to online services.
Download Withdata FileToDB
Windows 64 bit
Windows 32 bit
Linux .deb (For Debian, Ubuntu) 64 bit
Linux .rpm (For Red Hat, Fedora, SUSE) 64 bit
MacOS 64 bit
JSON Lines text format (JSONL), also called Newline-delimited JSON (NDJSON), or Line-delimited JSON (LDJSON). JSON Lines files may be saved with the file extension .jsonl, *.ndjson, *.ldjson.
Import data from JSON Lines (JSONL / NDJSON / LDJSON) file to PostgreSQL
Login to PostgreSQL -> Choose JSON Lines file -> Set PostgreSQL table -> Import JSON Lines to PostgreSQL
Choose PostgreSQL and logon.
Click “Wizard – 1 File To 1 Table” at task dialog.
Select the “JSON” file type.
then show the wizard.
1. Open a JSON Lines (JSONL / NDJSON / LDJSON) file.
Support large ( > 4GB ) JSON Lines file.
Here is the file’s content.
FileToDB will parse JSON Lines file.
2. Select a PostgreSQL table and config fields.
3. Preview data will be in PostgreSQL table.
4. Import JSON Lines data to PostgreSQL.
View imported data in PostgreSQL table
Convert JSON Lines (JSONL / NDJSON / LDJSON) to PostgreSQL in command line
Save “JSON Lines to PostgreSQL” session, then you can:
- Import JSON Lines (JSONL / NDJSON / LDJSON) to PostgreSQL in Windows command line.
- Import JSON Lines (JSONL / NDJSON / LDJSON) to PostgreSQL in Linux command line.
- Import JSON Lines (JSONL / NDJSON / LDJSON) to PostgreSQL in macOS command line.
Set scheduled tasks for converting JSON Lines (JSONL / NDJSON / LDJSON) to PostgreSQL
You can schedule and automate this “JSON Lines to PostgreSQL” conversion task by:
- Save session and create .bat (Windows) or .sh (Linux/macOS) file for “JSON Lines to PostgreSQL” conversion.
- Set scheduled task for “JSON Lines to PostgreSQL” conversion.
FAQ
More tools for JSONL / NDJSON / LDJSON.
Download Withdata FileToDB
Windows 64 bit
Windows 32 bit
Linux .deb (For Debian, Ubuntu) 64 bit
Linux .rpm (For Red Hat, Fedora, SUSE) 64 bit
MacOS 64 bit
JSON Lines → PostgreSQL reference
Type mapping
| Value kind | in JSON Lines | in PostgreSQL |
|---|---|---|
| Int | 1234 (number) | integer |
| Bigint | 9007199254740993 | bigint |
| Decimal | 1234.56 (number) | numeric(p,s) |
| Float | 1.234e10 (number) | double precision |
| Text | "text" (string) | varchar(n) |
| Long text | "multi-line\ntext" | text |
| Date | "2026-09-18" (string) | date |
| Datetime | "2026-09-18T14:30:00Z" (string) | timestamp |
| Binary | "base64:..." (string) | bytea |
| Boolean | true / false (boolean) | boolean |
| JSON | nested object on the same line | jsonb |
Dialect differences
JSON Lines is a file format and PostgreSQL is a database server, so the target has to be told the types the file never carried - the rows below are where the two sides diverge.
| Property | in JSON Lines | in PostgreSQL |
|---|---|---|
| port | — | 5432 |
| identifiers | Double quotes; backslash escapes (a newline inside a string... | "double quotes" |
| row limit | — | LIMIT n |
| dates | No date type: dates arrive as strings | timestamp, timestamptz, date, time |
| long text | — | TEXT |
| binary | Not supported natively - base64 inside a string | BYTEA |
| separator | Newline between records | — |
| encoding | UTF-8 by definition | — |
| typing | Same as JSON, but records cannot nest across lines | — |
| shape | Flat stream | Tables of rows and columns |
| ceiling | Streams, so it scales past what a single JSON document can ... | — |
Command line
| Side | Command |
|---|---|
| PostgreSQL | pg_dump or COPY ... TO |
| PostgreSQL (load) | COPY ... FROM |
JSON to PostgreSQL without the manual work
For batch jobs, large files and scheduling use the JSON to PostgreSQL converter — an offline desktop app for Windows, Linux and macOS. Free trial.