Sequences are arguably the most common biological data. An easy-to-use tool can greatly facilitate daily manipulation and analysis of biological sequences. Here we present SEQEL, a tool providing a convenient environment for editing, formatting, and rendering of DNA, RNA, and protein sequences. This is accomplished by extending the commonly used text editor, Emacs, which is available for Windows, Linux, and Mac OS.The unit tested ELISP source code for seqel is freely available from https://github.com/rnaer/seqel along with documentation.