Is converting NDJSON to psql free?

Yes. Files up to 10MB convert free with no account. There is a limit of five conversions per day per IP address.

Will my NDJSON data keep its types in psql?

Yes — that is the point. Whole numbers, decimals, dates and booleans are mapped to real psql types rather than everything becoming text. The mapping table above shows exactly what you get.

Do you store my file?

No. The file is written to a temporary directory, converted, and the directory is deleted as soon as your download has been sent.

Convert NDJSON to psql

Upload a .json or .ndjson file and get back a psql SQL script you can load straight into your database. Types are preserved rather than flattened to text. Free, no registration, up to 10MB.

1Upload your file

Click to upload or drag and drop

CSV, Excel, SQLite, SQL, DBF (max 10 MB)

2Choose target format

How your data is typed in psql

Generated from the converter's own psql type mapping — this is what it actually emits, not an example.

Your data	psql type
Whole number	BIGINT
Decimal (money)	NUMERIC(10,2)
Floating point	DOUBLE PRECISION
True / false	BOOLEAN
Date	DATE
Date and time	TIMESTAMP
Short text	TEXT
Long text	TEXT
Binary data	BYTEA

Working from an .ndjson file

Newline-delimited JSON is one complete object per line with no enclosing array, which is exactly what makes it appendable: a log or an export can keep growing without anything having to rewrite the end of the file.

→Each line is parsed on its own and blank lines are ignored, but a single malformed or truncated line fails the whole file - the usual outcome of copying a log that was still being written.
→Lines need not share their keys. The columns are what the records collectively use, and a record that omits one gets NULL in that column.
→A file that is one line long and wraps its array, {"rows": [...]}, is unwrapped into those rows rather than read as a single record.

Running the script through psql

psql is PostgreSQL's command-line client rather than the database itself, and the script is written to be fed straight into it. Everything here is about the tool you run, not about the server you run it against.

→From inside a session already open, \i dump.sql runs the file without leaving the prompt. The script contains no backslash meta-commands of its own, so nothing in it can collide with yours.
→There is no BEGIN and no COMMIT anywhere in the file. Statements commit as they go, so a failure halfway leaves the tables already created: pass -1 to wrap the whole load in a single transaction, or -v ON_ERROR_STOP=1 to stop at the first error instead of carrying on past it.
→The script switches standard_conforming_strings on itself instead of trusting the server default, so it behaves identically against a session that has been moved off it.
→It sets client_encoding to UTF8 for the same reason. The file is written as UTF-8 with nothing to announce that, and psql would otherwise decode it using whatever the client locale says.

Reading NDJSON

→JSON types are trusted: 1 and "1" stay different things.
→Numbers with a decimal point are read as exact decimals rather than floats.
→Both an array of objects and newline-delimited JSON work, and a wrapped array like {"data": [...]} is unwrapped automatically.
→Nested objects are kept as JSON rather than flattened into invented column names.

Writing psql

→Backslashes are left alone, because PostgreSQL treats them as ordinary characters — doubling them would corrupt every Windows path.
→Auto-increment columns become GENERATED BY DEFAULT AS IDENTITY.
→Binary data is written as bytea, and identifiers respect the 63-character limit.

What you get

A ZIP containing dump.sql, plus a README with the exact command to load it. If anything about your data needed a judgement call, a _warnings.txt explains it.

Load this dump into PostgreSQL:

  psql -U USER -d DATABASE -f dump.sql

Create the database first if it does not exist:

  createdb -U USER DATABASE

Questions

Is converting NDJSON to psql free?: Yes. Files up to 10MB convert free with no account. There is a limit of five conversions per day per IP address.
Will my NDJSON data keep its types in psql?: Yes — that is the point. Whole numbers, decimals, dates and booleans are mapped to real psql types rather than everything becoming text. The mapping table above shows exactly what you get.
Do you store my file?: No. The file is written to a temporary directory, converted, and the directory is deleted as soon as your download has been sent.