Desktop search tools search within a user's own computer files as opposed to searching the Internet. These tools are designed to find information on the user's PC, including web browser history, e-mail archives, text documents, sound files, images, and video.
One of the main advantages of desktop search programs is that search results arrive within a few seconds or less; Microsoft Windows search companion "can be some help, but it searches through Windows files and folders only, not e-mail or contact databases, and unless you enable the Indexing Service (in Windows 2000 or XP), the Windows search tool is extremely slow." MS Windows Vista enables the indexing service by default.
A variety of desktop search programs are now available; see this list for examples.
Desktop search is emerging as a concern for large firms for two main reasons: untapped productivity and security. On the one hand, users needs to be able to quickly find relevant files, but on the other hand, they shouldn't have access to restricted files. According to analyst firm Gartner up to 80% of some companies' data is locked up inside unstructured data — the information stored on an end user's PC, the directories (folders) and files they've created on a network, documents stored in repositories such as corporate intranets and a multitude of other locations. Moreover, many companies have structured or unstructured information stored in older file formats to which they don't have ready access.
Companies doing business in the United States are frequently required under regulatory mandates like Sarbanes-Oxley, HIPAA and FERPA to make sure that access to sensitive information is 100% controlled. This creates a challenge for IT organizations, which may not have a desktop search standard, or lack strict central control over end users downloading tools from the Internet. Some consumer-oriented desktop search tools make it possible to generate indexes outside the corporate firewall and share those indexes with unauthorized users. In some cases, end users are able to index — but not preview — items they should not even know exist.
Historically, full desktop search comes from the work of Apple Computer's Advanced Technology Group, resulting in the underlying AppleSearch technology in the early 1990s. It was used to build the Sherlock search engine and then developed into Spotlight, which brought automated, non-timer-based full indexing into the operating system.
Most desktop search engines build and maintain an index database to achieve reasonable performance when searching several gigabytes of data. Indexing usually takes place when the computer is idle and most search applications can be set to suspend indexing if a portable computer is running on batteries, in order to save power. There are notable exceptions, however: Voidtools' Everything Search Engine, which performs searches over only filenames — not the files' contents — for NTFS volumes only, is able to build its index from scratch in just a few seconds. Another exception is Vegnos Desktop Search Engine, which performs searches over filenames and files' contents without building any indices. The benefits to not having indices is that, in addition to not requiring persistent storage, more powerful queries (e.g., regular expressions) can be issued, whereas indexed search engines are limited to keyword-based queries. An index may also not be up-to-date, when a query is performed. In this case, results returned will not be accurate (that is, a hit may be shown when it is no longer there, and a file may not be shown, when in fact it is a hit). Some products, such as Lookeen, have sought to remedy this disadvantage by building a real-time indexing function into the software. There are disadvantages to not indexing. Namely, the time to complete a query can be significant, and the issued query can also be resource-intensive.
Desktop search tools typically collect three types of information about files:
- file and folder names
- metadata, such as titles, authors, comments in file types such as MP3, PDF and JPEG
- file content (for supported types of documents only)
To search effectively within documents, the tools need to be able to parse many different types of documents. This is achieved by using filters that interpret selected file formats. For example, a Microsoft Office Filter might be used to search inside Microsoft Office documents.
The sector attracted considerable attention from the struggle between Microsoft and Google. According to market analysts, both companies were attempting to leverage their monopolies (of web browsers and search engines, respectively) to strengthen their dominance. Due to Google's complaint that users of Windows Vista cannot choose any competitor's desktop search program over the built-in one, an agreement was reached between US Justice Department and Microsoft that Windows Vista Service Pack 1 would enable users to choose between the built-in and other desktop search programs, and select which one is to be the default.
- Conquer Information Overload, PC Magazine.
- Security special report: Who sees your data?, Computer Weekly, 2006-04-25.
- "Everything Search Engine". voidtools. Retrieved 27 December 2013.
- "Vegnos". Vegnos. Retrieved 27 December 2013.
- "Real-Time Indexing and Lookeen 8". Lookeen. Retrieved 26 October 2014.
- "The current state of video search", by Niall Kennedy
- "The current state of audio search", by Niall Kennedy
- "Search wars hit desktop computers". (Oct 2004) BBC News
- "Microsoft agrees to change Vista Desktop Search Tool" (Jun 2007)
- Keeper Finders, by Paul Boutin, Slate, December 31, 2004 — A comparison of Google, Ask Jeeves, HotBot, MSN and Copernic desktop search tools.
- GoebelGroup.com's desktop search tools comparison chart - Date of last update: 15 January 2007.
- A detailed comparison of desktop search tools - dated 2004.
- Comparison of desktop search software - Date of last update: March 2008
- TBox - DevTool, with ability to do fast search by text files