Is converting JSON to Postgres 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 Postgres?

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

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

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

Your data	Postgres 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.

The oldest PostgreSQL this loads into

Postgres is the informal spelling and the one most people type. Since the name says nothing about a version, the useful question for this page is which server releases the generated script runs on, and that is decided by the newest piece of syntax in it.

→The identity clause on auto-increment columns is the newest thing in the file, and it arrived in release 10. That is the floor for loading the script unedited.
→Everything else is far older: the hex escape the script uses for binary values has been accepted since 9.0, and jsonb, which is what a JSON column is declared as, since 9.4.
→On a server below the floor the script still loads if you delete the identity clauses by hand. The columns keep every value they were given, because each INSERT names them explicitly; they simply stop assigning new ones.

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 Postgres

→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 Postgres 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 Postgres?: Yes — that is the point. Whole numbers, decimals, dates and booleans are mapped to real Postgres 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.