Is converting JSON to PostgreSQL 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 JSON data keep its types in PostgreSQL?

Yes — that is the point. Whole numbers, decimals, dates and booleans are mapped to real PostgreSQL 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 JSON to PostgreSQL

Upload a .json or .ndjson file and get back a PostgreSQL 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 PostgreSQL

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

Your data	PostgreSQL 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 a .json file

A .json file can be almost any shape, and only a few of those shapes are a table. What the reader accepts, and what it does with the rest, is the thing worth knowing before you upload one.

→A wrapper is unwrapped only when the object has exactly one key and that key holds a list of objects. {"meta": {...}, "data": [...]} has two keys, so it is read as a single row instead.
→An array of strings, or an array of arrays, is refused with "Expected a JSON array of objects" - there are no column names in it to build a table from.
→Columns are the union of the keys seen in the first 10,000 records, in the order they first appear. A key that shows up only after that is not part of the table.

What the PostgreSQL script contains

The conversion produces one dump.sql with a README beside it, zipped. It is a script you can open, grep and edit before you run it rather than an archive a tool has to unpack, and it is deliberately sparing in what it declares.

→Every string column is declared TEXT, whatever length the source declared for it. PostgreSQL stores a short value in a TEXT column exactly as cheaply as in a VARCHAR, and an unbounded column cannot reject a row on load for being a few characters too long.
→Identifiers are all double-quoted, and even so a name on PostgreSQL's reserved list is given a trailing underscore: a column called user arrives as user_, order as order_, limit as limit_.
→A decimal column whose source declared no scale is given six decimal places rather than none, keeping whatever precision it did declare: NUMERIC(10,6) from a source that said 10, and NUMERIC(18,6) from one that declared neither. A scale of zero would have the server round 19.99 to 20 as it loaded.

Reading JSON

→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 PostgreSQL

→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 JSON to PostgreSQL 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 JSON data keep its types in PostgreSQL?: Yes — that is the point. Whole numbers, decimals, dates and booleans are mapped to real PostgreSQL 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.