The specifications that pinned the languages down - each tied to the standards body that issued it.
Debian's binding public promise to its users and the free-software community, first published in 1997, which commits the project to remain free software and which contains the Debian Free Software Guidelines that later became the basis of the Open Source Definition.
The Open Source Definition (OSD), derived from the Debian Free Software Guidelines, is the ten-point standard a software license must satisfy to be called open source.
XML is a W3C-standardized, simplified subset of SGML for representing structured data as text. First published as a Recommendation in 1998, it defines well-formedness and optional validity, and became a universal interchange format on the web.
HTTPS is HTTP secured with TLS, the protocol that encrypts web traffic; it grew out of Netscape's SSL and was standardized by the IETF as TLS in 1999.
Java 2 Platform, Micro Edition (J2ME, later Java ME), introduced by Sun in 1999, was a cut-down Java platform whose CLDC configuration and MIDP profile let small Java applications, especially games, run on hundreds of millions of feature phones.
XML-RPC is a simple protocol for making remote procedure calls over HTTP using XML to encode the calls and responses. Introduced by Dave Winer in 1998, it was a direct ancestor of SOAP and an influence on later web APIs.
XPath is the W3C expression language for addressing parts of an XML document by navigating its tree structure. Standardized in 1999, it underpins XSLT and XML querying and provides a compact, path-based syntax for selecting nodes.
XSLT is the W3C language for transforming XML documents into other XML, HTML, or text documents. Standardized in 1999, it is a declarative, rule-based language that uses XPath to select the parts of a source tree it transforms.
The Free Software Foundation's copyleft license for manuals, textbooks, and other documentation, designed to keep written works free in the same way the GNU GPL keeps software free; historically the original license of Wikipedia.
YAML Ain't Markup Language, a human-friendly, indentation-based data serialization format widely used for configuration in tools like Kubernetes and CI systems.
XML Schema (XSD) is the W3C XML-based schema language that succeeded DTDs for describing the structure and data types of XML documents. First a Recommendation in 2001, it is itself written in XML, supports namespaces, and adds a rich datatype system.
The plaintext markup of the Python documentation world, parsed by Docutils and used by Sphinx, designed to be readable in the raw yet powerful enough for structured documents.
Stuart Rackham's richer plain-text markup for technical books and documentation, with a full toolchain centered on the Asciidoctor processor.
The standardized family of Creative Commons licenses, built from the Attribution, ShareAlike, NonCommercial, and NoDerivatives conditions, plus the CC0 public domain dedication; CC BY-SA is the copyleft option used by Wikipedia.
A simplified permissive license written by the Internet Systems Consortium, functionally equivalent to the MIT and 2-clause BSD licenses but with even more concise wording; widely used by OpenBSD and as the default for npm packages.
H.264, also known as MPEG-4 Part 10 Advanced Video Coding, the most widely deployed video compression standard, jointly developed by ITU-T and MPEG and published as ITU-T H.264 and ISO/IEC 14496-10.
A permissive license published by the Apache Software Foundation that adds an explicit patent grant, contribution terms, and trademark and notice provisions to the basic permissive model.
John Gruber's plain-text-to-HTML lightweight markup syntax, designed for readability, that became ubiquitous in READMEs, chat, and documentation.
The OASIS XML standard for exchanging authentication and authorization assertions between identity providers and service providers, long the backbone of enterprise single sign-on.
OpenDocument Format is the open, XML-based standard for office documents (.odt, .ods, .odp), each a ZIP package of XML parts. Approved as an OASIS Standard in 2005 and as ISO/IEC 26300 in 2006, it is the native format of LibreOffice and a vendor-neutral alternative to proprietary office files.
Comma-Separated Values, the ubiquitous tabular plain-text format documented by IETF RFC 4180, along with its quoting and escaping rules.
The path-vector routing protocol that exchanges reachability between autonomous systems and stitches the independent networks of the internet into a single routing system.
Office Open XML is the XML-based file format family behind .docx, .xlsx, and .pptx, in which an Office document is a ZIP package of XML parts. Standardized as Ecma-376 in 2006 and as ISO/IEC 29500 in 2008, its fast-tracked ISO approval was deeply controversial.
SOAP is an XML-based messaging protocol for exchanging structured information between web services, built around an envelope structure and a stack of WS-* extension specifications. It was a cornerstone of enterprise web services in the 2000s.
WSDL is an XML format that describes a web service's operations, message types, and network endpoints, acting as the machine-readable contract that lets tools generate client and server code for SOAP services.
A weaker-copyleft GNU license, expressed as additional permissions on top of the GPL, that lets a covered library be linked into proprietary software while still requiring the library's own modifications to stay free.
A GNU copyleft license that extends the GPL to network-deployed software, requiring operators who modify a covered program and let users interact with it over a network to offer those users the program's source code.
A compact, schema-based binary serialization format that emerged from the Hadoop project in 2009, designed for efficient data exchange with built-in schema evolution.
The free and open instruction-set architecture begun at UC Berkeley in 2010, built around a small base integer ISA plus optional modular extensions, and maintained as a public standard by RISC-V International.
A public-domain dedication for software that attempts to waive all copyright rather than license them; alongside Creative Commons CC0 it represents the most permissive end of the open source spectrum.
JSON-RPC is a lightweight, transport-agnostic remote procedure call protocol that encodes requests and responses as JSON objects. Its 2.0 version is widely used in tooling such as the Language Server Protocol and in blockchain node APIs like Ethereum.
The Python standard interface between web servers and Python web applications or frameworks. First specified in PEP 333 (2003) and updated for Python 3 by PEP 3333 (2010), it decouples server choice from framework choice to promote application portability.
EditorConfig is a simple file format, the .editorconfig file, plus editor plugins, that lets a project share basic coding-style settings such as indentation, character set, and whitespace handling across many different editors and IDEs.
A file-level 'weak copyleft' open-source license originating from Netscape's 1998 open-sourcing of its browser; MPL 2.0 keeps modified files under the license while allowing combination with other code.
The authorization framework, defined in RFC 6749, that lets an application obtain limited delegated access to a user's resources without handling the user's password.
AMQP is an open, binary, wire-level protocol for message-oriented middleware, designed so that messaging clients and brokers from different vendors can interoperate. AMQP 1.0 became an OASIS Standard in 2012 and was later adopted as an ISO/IEC standard.
Tom's Obvious Minimal Language, a configuration file format created by Tom Preston-Werner that maps unambiguously to a hash table.
JavaScript Object Notation, a lightweight text-based data-interchange format standardized as ECMA-404 and IETF RFC 8259.
A browser mechanism, defined by the WHATWG Fetch standard, that uses Access-Control HTTP headers and preflight requests to safely relax the same-origin policy for web APIs.
The identity layer built on top of OAuth 2.0 that lets clients verify who a user is and receive their identity in a signed ID Token.
A rigorous, unambiguous specification of Markdown, created by John MacFarlane and others to end the chaos of incompatible Markdown dialects.
The fifth major revision of HTML, which added native audio, video, and canvas plus rich APIs, helping bring the plugin-and-Flash era to an end.
MQTT is a lightweight publish/subscribe messaging transport protocol designed for constrained devices and low-bandwidth, high-latency networks. Created in 1999, it became an OASIS Standard in 2014 and is now a backbone protocol of the Internet of Things.
A compact, URL-safe token format, defined in RFC 7519, for representing claims as a signed or encrypted set of three dot-separated parts.
A standard, language-agnostic description format for HTTP APIs, formerly Swagger, that lets humans and machines understand a service without reading its source code.
A Linux Foundation governance project, launched in 2015 by Docker, CoreOS, and others, that created open standards for container image and runtime formats so containers are portable across the whole ecosystem.
A query language and runtime, created at Facebook and open-sourced in 2015, that lets clients request exactly the data they need from a single typed endpoint.
A server-initiated message delivered to a device or web app even when it is not running, standardized for the web by the W3C Push API and delivered on mobile through platform services like Apple's APNs and Google's FCM.