Dynamic Table of Contexts is a free tool for supplementing a traditional table of contents for a text. It allows users to add or subtract index items based on XML encoding. This tool requires the creation of an account.

Micro-OCP (Oxford Concordance Program) was a major and historically important textual analysis tool for microprocessor computers. It enabled users to generate concordances, word lists and indexes, in addition to facilitating text markup in COCOA or other markup languages. Micro-OCP was written in FORTRAN, ran primarily in a DOS environment and could be ported to other operating systems including UNIX.

WordCruncher is long-standing text indexing, retrieval and analysis program offered by Brigham Young University. Its functions include tagging, contextual searching, collocation and analytical reporting, and its development has been active since the 1980s.

BIBCON was a key-word-out-of-context system for concordances developed in FORTRAN and available in the 1960s.  It was a modified version of another system, KWIC.

KWIC was an indexing and concordance tool available in the 1960s. Contrary to its name, KWIC functioned as a 'key-word-out-of-context' tool.

Annotate allows you to annotate documents and images online. You may also collaborate on documents and index files. Annotate supports PDF and MS Office file formats, and runs on all common web browsers.

Apache Lucene is a Java-based high-performance text search engine library. Lucene Core is a Java library providing powerful indexing and search features, as well as spellchecking, hit highlighting and advanced analysis/tokenization capabilities.

Solr is an open source enterprise search platform from the Apache Lucene project. It operates as a standalone full-text search server within an appropriate servlet container, such as Tomcat. Solr uses the Lucene Java search library at its core for full-text indexing and search, and has REST-like HTTP/XML and JSON APIs that make it easy to use from virtually any programming language.