Free online TOML to MDB converter

Applications that use Microsoft Access may require an .mdb database instead of a configuration file, so TOML data must be parsed and mapped into tables before it can be stored in MDB. The conversion is not a direct format change because TOML describes hierarchical configuration data, while MDB requires a relational database schema.

What the TOML format is

TOML (Tom's Obvious, Minimal Language) is a human-readable configuration format containing key-value pairs, tables, arrays, strings, numbers, booleans, and date/time values. It is commonly found in pyproject.toml files created by Python tools such as Poetry and PEP 517 build systems, Cargo.toml files created by Rust's Cargo package manager, and application-specific configuration files.

A TOML document may contain simple settings such as port = 8080, nested tables such as [database], arrays, and arrays of tables such as [[users]]. Its structure does not specify database tables, primary keys, relationships, indexes, or column types beyond the TOML value types.

What the MDB format is

MDB is the database format used by Microsoft Access versions through Access 2003 and by the Jet database engine. It stores tables, queries, forms, reports, indexes, relationships, and sometimes VBA modules in one file. MDB is useful when an older Windows application, Access installation, or Jet/ACE-based workflow specifically requires an .mdb file.

Access provides graphical table editing, SQL queries, relationships, forms, and reports. MDB is a legacy format, so newer projects generally use .accdb or another database engine unless compatibility with older software requires MDB.

How to actually convert TOML to MDB

Use the built-in online converter

1. Open the TOML-to-MDB converter on 101convert.com.
2. Upload the .toml file and start the conversion.
3. Download the generated .mdb file and open it in Microsoft Access or another Jet/ACE-compatible program.

This method is suitable when the converter can infer a usable schema from the TOML structure. Review the generated tables and field types before using the database for production data. Do not upload configuration files containing passwords, API keys, certificates, or other confidential values.

Use a controlled desktop workflow

1. Open the TOML file in a TOML-aware editor or parse it with a programming language that supports TOML. In Python 3.11 or later, the standard library can read it with tomllib.
2. Decide how the hierarchy maps to relational tables. A top-level table can become a table, an array of tables can become rows, and nested objects can become related tables or flattened columns. Simple top-level settings may belong in a single Settings table with name and value columns.
3. Export each chosen row set to CSV or insert it directly through an Access-compatible database connection. Preserve TOML strings as text, integers as long integers, decimal values as double-precision numbers, booleans as Yes/No fields, and date/time values as Access Date/Time fields.
4. In Microsoft Access, create a blank MDB database with File → New → Blank database, select the older .mdb format if prompted, and import each CSV through External Data → New Data Source → From File → Text File.
5. During the import wizard, choose the delimiter and text qualifier, set field names, select suitable data types, and define a primary key. Repeat the import for each table.
6. Create relationships under Database Tools → Relationships when nested TOML data was split into multiple tables. Save the database, close it, and reopen it to verify that tables and values remain intact.

For repeatable conversions, a script can parse the file and write CSV files. For example, a Python program can load the document with tomllib.load(open("config.toml", "rb")), transform arrays of dictionaries into rows, and write them with the csv module. Direct MDB creation requires an installed Microsoft Access Driver or another Jet-compatible ODBC provider; the script must execute on a system where that provider can create an MDB file.

Quality, compatibility, and limitations

The main risk is schema ambiguity. TOML does not identify rows or relationships, so an automatic converter may flatten nested values, serialize arrays as text, or create separate tables using assumptions that do not match the intended data model. Inspect arrays of tables, nested tables, duplicate keys, and empty arrays manually.

MDB also has legacy limits, including a maximum file size of approximately 2 GB and restrictions on field names, data types, and index definitions. Long TOML strings may exceed an Access Short Text field and need the Long Text type. TOML comments, ordering, whitespace, and formatting are not normally preserved because MDB stores values rather than the original configuration syntax.

After conversion, compare record counts, check null and empty values, verify date/time interpretation and character encoding, and test the MDB file with the exact application that will consume it. Keep the original TOML file because converting back from MDB will not reproduce the original TOML structure or comments.