Recently I had to rename maybe 20–30 files where I had to extract some fields from the file name, and then modify the numbers, like add 2000 to the number from the file, and change a few things in the file names. I gave a few apps a try, but I was not happy with how they were designed. A lot of buttons, a lot of options, a lot of configurations - it felt like the time I would spend learning how to use those apps would be similar to just writing a bash script in the end.

This is where I realized that the only things I need are Regular Expressions to extract the fields, and a simple script to modify the fields. So I decided to build a simple app that will allow me to do that. I called it RenameNinja, and I am happy to share it with you.

RenameNinja provides a simple interface where you can enter a regular expression to extract the fields, or write JavaScript code to modify those fields (or create new fields). After that, you tell the tool how to combine those fields into the new file name and press the Rename button.

RenameNinja automatically extracts additional fields for photos/images, videos and audio files.

The app is made for developers who know how to use Regular Expressions and JavaScript, or people who know how to ask an LLM to write the code for them.

Like most of the recent apps I have built, I provide a free unlimited trial version without any limited functionality. Just a reminder that I am a solo developer, and if you like the app, please consider buying the app. If you cannot afford it, just ignore the popup on every new session and keep using the app without any limitations.

Give it a try, and if you like it, there is a discount code that is valid until June 8th: RENAMENINJALAUNCHDISCOUNT (50% off).

Download the app from here.