What is a .ozm file?

A .ozm file is a money file made by Money by Zaweba, the offline personal finance app. Each one is a single SQLite database holding a whole household's or business's accounts, transactions, categories, rules, budgets and bills. It can optionally be encrypted with a password, and you open it with Money on Windows, Mac or Linux.

If someone has sent you a .ozm file, or you've found one on your computer, that's what it is: a complete set of home or business accounts in one file.

What's inside

Everything Money knows about a set of accounts lives in the file. That includes the accounts themselves with their opening balances and dates, every transaction with its payee, amount, category, memo and cleared or reconciled flag, the category tree, payee rules, monthly budgets, recurring bills and deposits, and the bank statement layouts the CSV wizard has learnt.

Amounts are stored as whole pence, so there are no rounding errors creeping in from fractions of a penny. Dates are stored as ISO text, the year, month, day form that sorts correctly and can't be misread. The file follows UK conventions whatever the computer is set to.

One file per household or business

Because each .ozm file is self-contained, you decide how to divide things up. A typical household keeps one file. A sole trader might keep a second file for the business so the two never mix, though Money's category tree also has a Business branch for those who prefer one file. Someone looking after an elderly parent's finances might keep a separate file for that too.

The File menu has New money file (Ctrl+N), Open (Ctrl+O), Recent files, Close file and Save a copy as. There's no Save command, because every change is written to the file straight away.

Opening one

To open a .ozm file you need Money by Zaweba, which is free software under the EULA. If Money is installed for your user, double-clicking a .ozm file in File Explorer opens it, since the installer links the extension to the app. Otherwise, start Money and use File, then Open.

If the file has a password, Money asks for it. The encryption is SQLCipher 4 with AES-256, and without the right password the file won't open at all. There's no way round that, which is the point.

The Mac and Linux version opens the same files, encrypted or not, so a .ozm file made on Windows can be opened on a Mac and back again.

Backing it up

The simplest backup is a copy of the file. Money makes one for you whenever you close the file and when you use File, then Back up now, keeping the last 10 in a backups folder next to it. File, then Show the backups folder, opens that folder. Each backup is itself a .ozm file, so restoring is a matter of opening the copy you want.

For protection against a failed drive, copy the file somewhere else as well, such as an external drive. Because the file on disk is the whole story, that copy is complete.

Things to watch with .ozm files

Don't open the same file in two places at once, for example from a shared folder on two computers, as you'll end up with changes that can't be combined. Don't rename the extension, or the file association won't recognise it. And if a .ozm file has a password you don't know, it can't be opened; Money is deliberately strict about that.

In short, a .ozm file is Money by Zaweba's way of keeping your finances in something you can see, copy and hold on to.