Welcome to the Heureca Extension! The shortcut to mystery cache solutions!

Welcome to the Heureca Extension! The shortcut to mystery cache solutions!

The idea to the extension was born when I was annoyed to have to jump between several web pages every time I wanted to solve a mystery or multi cache. I did paste all the answers into the notes section, scrolling back and forth and save and calculate and ...

Wouldn't it be nice to have a form instead to enter the answers directly and then use some tools to turn the answers into coordinates?

With the extension this became possible! Formulas included in the description will be detected in most cases. The will be listed next to the cache description in a form for easy access.

And not only this, but over the last year more and more features had been added that shorten the time to get to the solution and have more fun outside!


Heureca provides a wide range of decryption tools and calculation support. To make it simple it will try to show only those to the user that are relevant.

Here is a list of some of the features.


Coordinates including formulas
Besides of normal coordinates this also shows and handles coordinates that contain variables and formulas. Users can enter variable values and the formulas will be resolved automatically.
Calculate the opposite point of the earth.
Coordinate Projection
Calculate coordinate projection from a given point.
What3Words Coordinates

Text Analysis

Character Count
The number of characters in a text.
Character Sum
Calculates each character's position in the alphabet and sums them all up.
Letter Value
Calculates each position of a single character in the alphabet.
Word Count
Counts the number of words in a text.
Displays the positions of a letter in a text.


Does simple mathematical operations like adding values, etc.
Cross Sum
Calculates the cross sum.
Iterated Cross Sum
Calculates the cross sum of a number iteratively until the value is a single digit number.
Alternating Cross Sum
Takes the digits from a number and adds every second digit, but subtracts every other.
Calculates the range between two dates
Calculates with Roman numbers


Converts ASCII codes to characters.
Base 64 decoding which is often used for images or when transferring data over the internet.
Binary to decimal conversion.
Octal to decimal conversion. This may actually take an input to specify the base to allow conversions from number systems with different bases as well.
Hexadecimal to decimal conversion.
Morse Code
Morse code decoding.
Phone pad decoding.
Rail Fence
Zick Zack decoding


Caesar Cipher / Rot13
The classical Caesar algorithm that exchanges every character with the one from a shifted alphabet.
Similar as Caesar, but takes all visible characters from the ASCII alphabet into account.
Similar as Caesar, but takes all numbers as well as characters into account.
Similar as Caesar, but takes only numbers into account.
A transposition algorithm that shuffles the characters.
A transposition algorithm that shuffles the characters.
Converts between QWERTY and Dvorak keyboard assignment.


The Vigenère cipher.


Heureca also provides an auto processor that will try all processors and list the reasonable responses so that it is easy to have an overview.

Stay tuned, there will be more ...