Useful websites for puzzle solving

This is just a collection of links to websites that I've found to be useful in solving various puzzle based geocaches. It's not intended to be a puzzle solving guide, but I have included some links to guides where appropriate. It's also a somewhat selective collection, as it concentrates on less common and more powerful tools.

WARNING: I have no control over the pages that are linked to from this site. I have tried most of them myself without any problems, but over time, things change. So please exercise caution when visiting websites, and particularly when downloading files. Use an antivirus application on your computer. If you do find a malicious site or file, please let me know and I'll remove the link.

Puzzle Solving Guides

There are plenty of websites which offer guidance on solving geocaching puzzles, such as the following:

General Puzzle Tool Sites

There are also a number of websites which provide or link to tools which may be useful.

  • Geocaching Toolbox - Codes, ciphers, coordinate conversions & more
  • Purple Hell - The Riddle Tools section of this site was a massive resource of information useful in solving all kinds of puzzles. Unfortunately they seem to have lost their domain registration, and it's now occupied by a domain squatter. The good news is that the site is still mostly available via the Internet Archive's Wayback Machine (just follow the links!).
  • Red Luth Riddle Tools - Chock full of puzzle solving goodness.
  • Rick Richardson's Linux tools for geocaching - Linux based geocaching and puzzle tools


See the separate page on ciphers.

Number Coding Systems

See the separate page on number coding systems

Writing Systems

Different writing systems can also be considered codes, as they substitute new symbols for individual English letters.

Omniglot is a massive resource for real and artificial written languages - here's a small sample of some that have been used in puzzles:

Cirth Runes (from The Lord Of The Rings) Cirth
Uruk Runes (The Lord Of The Rings) Uruk
Tengwar (The Lord Of The Rings) Tengwar
Klingon (from Star Trek) Klingon
Futurama alien alphabet Futurama alien alphabet
Visitor script (from the TV series "V") Visitor



Dancing Men

One of the more famous codes/substitution ciphers is the "Dancing Men" cipher from the Sherlock Holmes story of the same name. There is a nice tool for encoding and decoding this at Purple Hell.

Maritime Signal Flags


Historically, there have been a number of systems of flags used to communicate visually between ships. There are a number of places that you can find the International Code of Signals in use today, but if you are thrown a more obscure code, then you need to know where to look. Good places to try are quadibloc  and the Peabody Essex Museum.



This site has descriptions for a number of 2D barcodes.

For an online decoder, try the ZXing online decoder. It decodes barcode images in most common formats, including UPC-A, UPC-E, EAN-8, EAN-13 , Code 39, Code 93, Code 128, QR Code, ITF, Codabar, RSS-14, Data Matrix, PDF 417 and Aztec.

Alphametics (Cryptarithms)

There's a good solver for addition puzzles here, whch even allows you to solve in bases other than 10. For alphametics involving operations other than addition, try the applet here.

Projection and Datum Conversion

Useful Sites:


Typical Problems:

  • Given a point, a bearing and a distance, project a new point: Use the tool at Movable Type
  • Given two points, and a bearing from each point, find the point where the lines of bearing intersect: Use the tool at Movable Type or Gazza's Great Circle Calculator
  • Given three points, and a distance from each, find the point by trilateration: I don't know of any online tools for this, so I use OziExplorer. Enter each point as a waypoint, and in the edit dialog, set a proximity circle with radius equal to the distance from that point. Then look for where the circles intersect.


General manipulation of large numbers, or high precision? Try Wolfram Alpha.

Image Analysis

For images, I find the GIMP and Irfanview (and it's plugins) to be invaluable. If you don't want to install applications on your PC, there are online image editors that will do some of what you need. For example pixlr let's you determine RGB values for colours, but doesn't import animated GIFs properly. To check for info hidden in image metadata (such as EXIF and IPTC fields), you really can't go past Jeffrey's Exif Viewer.

JPEGsnoop decodes JPEG images into component sections. The main use that I've found for puzzles is the abillity to search for images embedded in other files, multiple images in a file, or to check if there is extra data at the end of a file.

If you are trying to determine whether a photo has been modified, then error level analysis may be able to give some insight. There is a tool at fotoforensics, and a description of how it works at infosecinstitute.


Steganography is the practice of concealing information within a file, message, or image. In particular, there are a number of tools available for embedding data into images. There is a large list of Steganographic software at JJTC.

WARNING: I've had a report from one user of malware associated with Stegdetect, but have been unable to confirm this, so I've left the link active. Before downloading or running any of these files, make sure that you have appropriate antivirus protection in place. If you have any doubt about a link or file, do not download it!

Downloadable encryters/decryters:

Some of the more popular online encrypter/decrypters are:


Name/link What can it hide? Container Other Note
Steganografie (Kwebbel) Any file PNG Image Accepts a JPG image to create the container
Mozaiq Text message PNG image Accepts any image to create the container
HideImage (Incoherency) Any image PNG image Accepts any image (except JPG) to create the container
Mobilefish Text or image PNG image Accepts any image to create the container
ManyTools Text or image PNG image Accepts any image to create the container
UtilityMill     Not working at present


Stenagography detection tools:

  • StegDetect - Can detect data embedded using jsteg, jphide, invisible secrets, outguess, F5, appendX and camouflage. Please read the warning above!
  • StegSpy


Magic Eye (Stereograms)

If you have trouble seeing the 3D images in autostereograms (commonly known as Magic Eye images), there are utilities that will pull the hidden image out, such as this one.

Sound Analysis

For analysing sound files, there's a Java applet sonogram viewer that you can launch from your web browser, though it doesn't accept MP3 format. If you're willing to install an application, then try SonicVisualisaer.

Other Sites

Here are a few other websites that are generally interesting.

Puzzle Wiki - also has some links to various tools.

Cross+A is a tool that lets you create and solve a number of grid and word based puzzles. I've not tried the tool, but this page has a good description of a number of grid puzzles, including those invented by Nikoli and others.

Cryptii has an online tool,  to convert between dozens of different encodings, including Morse, Hexadecimal, Roman numerals, Pigen, Baudot/Murray, and even Navajo code talker.


National Puzzlers' League

American Crytpogram Association

Sites No Longer Useful

The pages at have disappeared, which is a shame as they were a great reference for punched cards, morse and braille variants, and maritime flags.


free counters

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