The tools below are useful when solving various types of puzzles. Be cautious when using them: too much automation can take the fun out of puzzling.

Word Tools

• OneLook and OneLook Reverse Dictionary
• Nutrimatic
• Qat
• Regex Dictionary
• Mystery Hunter's Word Search
• Base Finding Tools of the NPL
• MoreWords
• RhymeZone
• tools.qhex.org has some word search tools
• CrosswordNexus Wikipedia Regex Search
• Internet Anagram Solver
• puz.link

Crosswords and Cryptics

• xword.group
• Crossword Parser
• OneAcross Crossword Clue Search
• Crossword Tracker Crossword Database
• Crossword Nexus
• wordplays Crossword Solver
• Crossword Genius
• XWord Info
• CrossBar Cryptic Crossword Solver

Ciphers

• quipqiup Cryptogram Solver
• dCode
• Rumkin Cipher Tools
• CyberChef
• Cryptii

Image Search Tools

• TinEye Reverse Image Search
• Yandex Image Search, has reverse image search through clicking the camera icon
• Google Image Search, has reverse image search through clicking the camera icon
• qhex's Image Search tool
• Huntress, a browser extension
• Search by Image, a browser extension

Audio Search Tools

• Shazam
• Midmoi
• Musipedia
• Classical Music Tune Lookup

Libraries

• grilops Grid Logic Puzzle Solver library
• solvertools
• puzzle-tools

Other Tools

• /dev/joe's MIT Mystery Hunt Puzzle Index
• Noq, logic puzzle solver
• tools.qhex.org has some logic puzzle tools
• Sets of Things