Blue box is an early phreaking tool that simulates a telephone operator's dialing console.

Blue box may also refer to:

Technology

• Link Trainer or Blue Box, a flight simulator

• Blue Box, a Mac OS 8 emulation layer from the Rhapsody OS which became the Mac OS X Classic Environment

• MXR Blue Box, an octave effect for electric guitars

• Nickname of Hessdalen AMS, as it uses a blue container

Entertainment

• TARDIS, or "the blue box", a time machine and spacecraft in the British TV series Doctor Who

• Blue Box (novel), a Doctor Who novel by Kate Orman

• Blue Box (album), a 1996 album by Kate Ceberano

• Blue Box (manga), a manga series by Kouji Miura

• Bluebox Limited, a film production company

Other uses

• Blue Box, common name for the tree species Eucalyptus baueriana and Eucalyptus magnificata

• Blue box (WTO agreement), a subsidy category of the World Trade Organization

• Blue box recycling system, initially a waste management system used by Canadian municipalities

• A nickname for Kraft Dinner packaged stovetop macaroni and cheese

• A British police box

• A term for Handcuff covers

• A severe thunderstorm watch, in meteorology

• JNF collection boxes, Jewish National Fund blue charity collection boxes

• Blue Box, a gift given with each purchase made at Tiffany and Co.