LTEX provides offline grammar checking of various markup languages using LanguageTool (LT). LTEX can be used standalone as a command-line tool, as a language server using the Language Server Protocol (LSP), or directly in various editors using extensions. LTEX currently supports BibTEX, ConTEXt, LATEX, Markdown, Org, reStructuredText, R Sweave, and XHTML documents. A classic use case of LTEX is checking scientific LATEX papers.