1 Overview
1.1 Definition and purpose
Clojure/conj is the annual conference dedicated to the Clojure programming language. First held in 2012, the event serves as a central gathering for developers, language designers, and community members to share knowledge, discuss new developments, and network. The conference typically spans two to three days and features keynotes, presentations, workshops, and social activities. Its primary purpose is to advance the understanding and adoption of Clojure, a dialect of Lisp that runs on the Java Virtual Machine (JVM), as well as to foster collaboration within the community.
1.2 Relation to the Clojure ecosystem
Clojure/conj is closely tied to the broader Clojure ecosystem, which includes the language itself, its core libraries (e.g., clojure.core, core.async), popular tools (Leiningen, Clojure CLI), databases (Datomic), and frameworks (Ring, Compojure, Reagent). The conference provides a platform for announcing new language features, libraries, and tooling, and for discussing the practical applications of Clojure in areas such as functional programming, concurrent systems, and data processing. It is organized by the Clojure core team and has historically been hosted by Cognitect (later Nubank), the company employing Clojure's creator Rich Hickey and other key contributors.
2 History
2.1 Origins (2012)
The first Clojure/conj was held in 2012 in Austin, Texas, organized by Cognitect (then known as Relevance, later renamed). The event was conceived as a successor to earlier Clojure gatherings, including the Clojure "conj" (a play on "conjunction") that had been held in 2010 and 2011 in different formats. The 2012 conference marked the first formal, multi-day conference dedicated solely to Clojure, attracting over 200 attendees and featuring talks from prominent community members.
2.2 Key milestones
2.2.1 Cognitect era (2012–2020)
During the Cognitect era, Clojure/conj was held annually in various U.S. cities, primarily Austin, Texas, with one edition in Philadelphia (2016). The conference grew in size and scope, typically attracting 300–500 attendees. Key milestones included the announcement of core.async at the 2012 conference, the introduction of Clojure spec at the 2014 conference, and the preview of Clojure 1.10 at the 2018 conference. Cognitect also managed the conference's logistics, sponsorship, and program curation.
2.2.2 Nubank era (2020–present)
In 2020, Nubank, a Brazilian fintech company, acquired Cognitect. The conference continued under Nubank's auspices, with the 2020 edition transitioning to a virtual format due to the COVID-19 pandemic. Nubank maintained the conference's traditions, including Rich Hickey's keynotes, and introduced new initiatives such as scholarship programs and virtual networking opportunities. The 2023 edition marked a return to in-person gatherings in Austin, with a hybrid component for remote attendees.
2.3 Virtual editions during the pandemic
2.3.1 Transition to online format (2020)
The 2020 Clojure/conj, originally scheduled as an in-person event in Austin, was forced to move online due to global travel restrictions and public health concerns. The organizers adopted a fully virtual format, streaming recorded talks and holding live Q&A sessions via video conferencing platforms. The transition was generally well-received, though some attendees missed the informal networking opportunities of in-person events. The virtual format also allowed a wider international audience to participate, with no travel costs.
2.3.2 Hybrid experiments (2021–2022)
In 2021 and 2022, Clojure/conj experimented with a hybrid model, offering both an in-person component (with limited capacity and safety measures) and a virtual track. The 2021 edition was held in a smaller venue in Austin, with a reduced number of attendees, while the virtual option was free or low-cost. The 2022 edition similarly combined a modest in-person gathering with an online stream. These hybrid experiments allowed the conference to maintain community engagement while accommodating those unable to travel.
3 Organization
3.1 Organizing team
3.1.1 Clojure core team
The Clojure/conj is organized by members of the Clojure core team, including Rich Hickey (language creator), Stu Halloway (Cognitect co-founder), Alex Miller, and other developers employed by Cognitect/Nubank. They are responsible for selecting keynote speakers, setting the conference agenda, and overseeing the technical and logistical aspects. The core team's deep involvement ensures that the conference aligns with the language's development priorities.
3.1.2 Community volunteers
Community volunteers play a significant role in the conference's execution. Volunteers assist with registration, session moderation, live captioning, video recording, and social media coverage. Many volunteers are experienced Clojure developers who contribute their time to help the community. The volunteer program also includes a "conj crew" that handles on-site operations during in-person editions.
3.2 Sponsorship structure
3.2.1 Gold, Silver, and Bronze tiers
Sponsors support Clojure/conj through a tiered system. Gold sponsors (e.g., Nubank, Cognitect, Datomic) provide the largest financial contributions, often with premium branding and exhibitor space. Silver and Bronze sponsors receive proportional recognition, including logo placement on the conference website, mentions in promotional materials, and opportunities for hosted social events. Sponsorship fees cover venue costs, speaker travel, catering, and other operational expenses.
3.2.2 In-kind sponsors
In-kind sponsors contribute goods or services rather than cash. Examples include video production companies that record and stream talks, travel agencies that book speaker flights, and local businesses that provide catering or venue discounts. In-kind sponsors are acknowledged alongside cash sponsors on the conference website and in printed programs.
3.3 Venues and locations
3.3.1 Austin, Texas (2012–2015, 2017–2019)
Austin has been the primary host city for Clojure/conj, hosting the conference in 2012, 2013, 2014, 2015, 2017, 2018, and 2019 (as well as the post-pandemic return in 2023). Venues have included the Hilton Austin, the Austin Convention Center, and the Long Center for the Performing Arts. Austin's central location in the United States, its vibrant tech scene, and its proximity to Cognitect's headquarters (originally based in Dallas) made it a natural choice.
3.3.2 Philadelphia, Pennsylvania (2016)
In 2016, the conference was held in Philadelphia at the Loews Philadelphia Hotel. This single departure from Austin was partly intended to reach a different audience on the East Coast and to celebrate the growing Clojure community in the Northeastern United States. The venue provided ample space for talks, workshops, and social events.
3.3.3 Other locations and virtual
No other in-person locations have been used for the main conference, though satellite events (such as Clojure/conj Europe or regional meetups) have been organized independently. From 2020 to 2022, the conference adopted virtual or hybrid formats, with the in-person component remaining in Austin when feasible.
4 Program and content
4.1 Keynote speakers
4.1.1 Rich Hickey keynotes
The most anticipated keynote of each Clojure/conj is delivered by Rich Hickey, the creator of Clojure. His keynotes typically focus on language philosophy, upcoming features, and broader themes in software design. Notable keynotes include "Effective Programs" (2012), "The Language of the System" (2014), "Maybe Not" (2018), and "Open, Closed" (2023). Hickey's talks are known for their depth, wit, and occasional use of visual aids such as whiteboard diagrams.
4.1.2 Guest keynotes from industry leaders
Beyond Hickey, the conference invites guest keynoters from the wider software industry. Past speakers include Rich Hickey (repeated), Stuart Halloway, Paul Phillips, Sasha Laundy, and Carin Meier. These keynotes cover topics such as functional programming in other languages, software architecture, and career development. The guest keynotes are selected to provide diverse perspectives while remaining relevant to the Clojure community.
4.2 Talk tracks
4.2.1 Technical talks
Technical talks form the core of the conference program. They cover a wide range of topics, including Clojure language features (e.g., transducers, spec, core.async), libraries and frameworks (e.g., ClojureScript, Ring, Compojure, Reagent, Fulcro), concurrent and parallel programming, data science, web development, and tooling (e.g., CIDER, figwheel-main, deps.edn). Presenters are typically experienced Clojure developers and open-source contributors.
4.2.2 Community talks
Community talks highlight the human side of Clojure development. Topics include lessons learned from real-world Clojure deployments, stories of adopting Clojure in non-traditional environments, and reflections on the Clojure community's culture. These talks often include humorous anecdotes or lighthearted observations (e.g., "The Joy of REPL-Driven Development" or "How I Learned to Stop Worrying and Love Persistent Data Structures").
4.2.3 Lightning talks
Lightning talks are short (5–10 minute) presentations given by attendees. They cover a wide variety of subjects, from quick library demos to personal projects, humorous rants, and "show and tell" sessions. Lightning talks are a fixture of the conference and provide an opportunity for less experienced speakers to present in a low-stakes environment.
4.3 Workshops and tutorials
4.3.1 Beginner workshops
Half-day or full-day workshops are offered for attendees new to Clojure. These workshops cover fundamentals such as syntax, data structures, functions, and REPL usage. They are led by experienced Clojure educators and often include hands-on exercises using tools like Leiningen or the Clojure CLI.
4.3.2 Advanced deep dives
Advanced workshops target experienced Clojure developers. Topics have included "Building a Web Application with ClojureScript and Reagent," "Macros and Metaprogramming," "Distributed Systems with Datomic," and "Performance Tuning and JVM Interop." These sessions assume familiarity with core Clojure and focus on practical, in-depth techniques.
4.4 Social events
4.4.1 Evening gatherings
Clojure/conj traditionally hosts evening social events, often sponsored by companies in the ecosystem. These may include receptions at the venue, hosted dinners at local restaurants, or informal meetups at nearby bars. The evening gatherings are an important networking opportunity, allowing attendees to discuss the day's talks and form new connections.
4.4.2 Birds of a feather sessions
Birds of a feather (BoF) sessions are informal, attendee-organized discussions on specific topics. They are scheduled during breaks or in parallel with the main program. Common BoF topics include "Clojure in the Enterprise," "Functional Design Patterns," "ClojureScript and Mobile Development," and "Open Source Contribution Workflow." BoF sessions encourage community-driven knowledge sharing.
5 Notable editions
5.1 Clojure/conj 2012
5.1.1 First conference
The inaugural Clojure/conj took place November 15–17, 2012, in Austin, Texas. It attracted approximately 250 attendees and featured 20+ talks. The conference set the template for future editions: two days of talks plus one day of workshops. Rich Hickey delivered the opening keynote.
5.1.2 Introduction of core.async
At the 2012 conference, Rich Hickey and other developers introduced core.async, a library for asynchronous programming using channels and go blocks inspired by the Go language. The announcement was a major highlight, and core.async quickly became one of the most adopted Clojure libraries, enabling simpler concurrent and event-driven code.
5.2 Clojure/conj 2014
5.2.1 spec announcement
The 2014 edition (held in Austin) saw the announcement of Clojure spec, a new library for describing the structure of data and functions, with validation, generative testing, and error reporting capabilities. Rich Hickey's keynote "clojure.spec – The Next Big Feature" generated considerable excitement. Spec was released as a alpha feature in Clojure 1.9.
5.2.2 Clojure 1.7 release
Clojure 1.7, released shortly before the 2014 conference, introduced transducers—a new way to compose data transformation operations without intermediate collections. Talks at the conference explained transducers and their use, and the topic remained a focus of discussion throughout the event.
5.3 Clojure/conj 2018
5.3.1 Clojure 1.10 preview
The 2018 conference (Austin) featured a preview of Clojure 1.10, which included improvements to spec, improved error messages, and new functions. Alex Miller gave a detailed talk on the upcoming release. The preview allowed community members to test and provide feedback ahead of the official release.
5.3.2 Datomic updates
Significant updates to Datomic, the distributed database built on Clojure concepts, were presented. Stu Halloway discussed new features such as Datomic Cloud, which runs on AWS, and the introduction of the "Datomic J" client for Java. The conference also included tutorials on Datomic's data model and query language.
5.4 Clojure/conj 2023
5.4.1 Post-pandemic return to in-person
Held in November 2023 in Austin, Clojure/conj returned to a fully in-person format after three years of virtual or hybrid editions. Attendance exceeded 400, a new record. The conference maintained a hybrid streaming option for remote participants.
5.4.2 New tooling presentations
The 2023 edition showcased new tools and libraries, including the tools.build library (a build tool replacement for Leiningen), improvements to the Clojure CLI, and early work on babashka (a Clojure scripting tool). There was also a significant focus on ClojureScript and full-stack development with projects like re-frame and shadow-cljs.
6 Registration and attendance
6.1 Ticket types
6.1.1 Early bird
Early bird tickets are offered at a discounted price to encourage early registration. They typically go on sale 6–9 months before the conference and are limited in number. Early bird pricing has ranged from $150 to $300 depending on the edition.
6.1.2 Standard
Standard tickets cover the full conference (talks, workshops, and social events). Prices have varied, generally between $300 and $600 for in-person editions, with lower rates for virtual-only attendance. The price includes catering (lunch and snacks) for in-person attendees.
6.1.3 Student/scholarship
Student tickets are offered at a reduced rate (often $50–$100) for full-time students. Additionally, a scholarship program (initiated in the Nubank era) provides free tickets to underrepresented groups in tech, including women, people of color, and individuals from low-income backgrounds. Scholarship recipients also receive travel and accommodation support when possible.
6.2 Code of conduct
Clojure/conj has a published code of conduct that prohibits harassment, discrimination, and disruptive behavior. It covers both in-person and virtual interactions. The code is enforced by conference staff, and attendees are encouraged to report violations. The code is prominently displayed on the conference website and read aloud at the opening of each in-person edition.
6.3 Diversity initiatives
The conference has taken steps to increase diversity among speakers and attendees. Initiatives include the scholarship program (mentioned above), a dedicated diversity track (featuring talks on inclusive software development), and partnerships with organizations such as Women Who Code and Out in Tech. The proportion of underrepresented speakers has increased over the years, though the Clojure community remains predominantly male.
7 Legacy and impact
7.1 Influence on Clojure development
Clojure/conj has directly influenced the evolution of the Clojure language. Major features such as core.async, spec, and transducers were first announced or demonstrated at the conference. Feedback from talks and informal conversations at BoF sessions has informed decisions about language design, library development, and tooling. The conference also serves as a testing ground for new ideas before they are widely released.
7.2 Community building
The conference has been instrumental in building and sustaining the Clojure community. It provides a regular opportunity for geographically dispersed developers to meet face-to-face, strengthening personal and professional relationships. Many collaborations, open-source projects, and job placements have originated from connections made at Clojure/conj. The event has also inspired regional Clojure conferences (e.g., Clojure/Denver, Clojure/NYC, Clojure/conj Europe) and local user groups.
7.3 Archives and recorded talks
All talks from Clojure/conj are recorded and made publicly available on YouTube (via the official Cognitect/Nubank channel) and the conference website. The archives serve as an invaluable resource for the Clojure community, providing access to keynotes, technical deep dives, and community stories for those unable to attend. The recordings are frequently referenced in online discussions, tutorials, and learning materials.