Open source companies attract a specific kind of engineer: the kind who wants their work to reach millions, not sit behind a corporate firewall. When a company's core product is open source, everything changes. The code is public. The community is a stakeholder. And the engineers building it know that their contributions live far beyond any single employer.
For engineers who care about transparency, community impact, and building tools that others can learn from and improve upon, open source culture isn't a nice-to-have — it's a top priority. These companies contribute to the broader ecosystem rather than keeping everything behind closed doors. They attract developers who believe that the best software is built in the open.
We identified 9 AI and tech companies in our Culture Directory that genuinely embody open source culture. Not companies that release the occasional side project on GitHub, but companies where open source is central to what they build, how they hire, and how they think about engineering. Here's who they are, what it's really like to work there, and how many roles they're hiring for right now.
The Full List
Below are all 9 companies sorted by Glassdoor rating. The colored bars give you an at-a-glance read: green for 4.0 and above, amber for 3.5–3.9, and red for below 3.5.
| # | Company | Glassdoor | WLB | Jobs | Size |
|---|---|---|---|---|---|
| 1 | LangChain | 4.6 |
4.0 | 84 | Small (~230) |
| 2 | Weaviate | 4.3 |
4.2 | 3 | Small (~110) |
| 3 | Together AI | 4.1 |
3.8 | 48 | Small (~150) |
| 4 | Airbnb | 4.1 |
4.0 | 243 | Large (~7,300) |
| 5 | Mistral AI | 4.0 |
3.6 | 142 | Small (~100) |
| 6 | Modal | 4.0 |
3.8 | 31 | Small (~110) |
| 7 | Replit | 4.0 |
3.9 | 85 | Small (~200) |
| 8 | Vercel | 3.9 |
3.4 | 79 | Mid (~600) |
| 9 | Hugging Face | 3.8 |
4.1 | 14 | Small (~400) |
A few things stand out. LangChain leads with a 4.6 Glassdoor rating — the highest on this list and one of the highest in our entire database. Meanwhile, Hugging Face has the lowest overall Glassdoor score (3.8) but the second-highest work-life balance rating (4.1), suggesting that while there are areas for improvement, the company genuinely respects boundaries. And Airbnb proves that open source culture isn't limited to startups — at 7,300 employees, it's the largest company on this list and still maintains strong ratings across the board.
Company Deep-Dives
Let's look at each company in detail. We've ordered them by Glassdoor rating, from highest to lowest, with real employee quotes from Glassdoor reviews.
1. LangChain
LangChain is the framework that made building LLM applications accessible to every developer. With LangSmith for observability and LangGraph for agent orchestration, the company has built an entire ecosystem around open source AI tooling. At ~230 employees, LangChain has grown rapidly but maintains the energy of an early-stage startup. The open source community is massive — tens of thousands of developers use the framework daily — which means engineers here see their work adopted at a scale most companies can only dream of.
2. Weaviate
Weaviate is the open source vector database that powers search and RAG applications for companies worldwide. The entire database engine is open source, not just a wrapper or side project. At ~110 employees and fully remote, Weaviate has built one of the strongest async-first cultures on this list. The company explicitly prioritizes timezone respect, documentation-heavy workflows, and psychological safety — values that show up clearly in their 4.2 WLB score, the highest of any company here.
3. Together AI
Together AI is building the infrastructure layer for open source AI. Their platform lets developers fine-tune, train, and run open models at scale — and they've been instrumental in training and releasing several notable open source models. At ~150 employees, the team is deeply engineering-driven, with a flat hierarchy and a genuine commitment to keeping AI open. If you believe the future of AI should be accessible to everyone, not locked behind API walls, Together AI is walking the talk.
4. Airbnb
Airbnb might surprise people on an open source list, but the company has a deep history of contributing to the ecosystem. Projects like Airflow (now Apache Airflow), Superset, and numerous internal tools have been open sourced and adopted industry-wide. At ~7,300 employees, Airbnb is by far the largest company here, and its "Live and Work Anywhere" policy makes it one of the most genuinely remote-flexible large companies in tech. The 4.0 WLB score and 4.1 Glassdoor rating reflect a mature engineering culture that values open contribution.
5. Mistral AI
Mistral AI is the Paris-based company that proved you don't need billions in compute to compete at the frontier. With Mixtral, Mistral Large, and a series of open-weight models, Mistral has become the European standard-bearer for open source AI. At only ~100 employees, this is a tiny team punching far above its weight class. The culture is intensely engineering-driven, with minimal process and maximum autonomy. The 3.6 WLB score reflects the reality of competing with OpenAI and Anthropic — the pace is fast — but for engineers who thrive in high-intensity environments, the upside is enormous.
6. Modal
Modal is a cloud platform for running generative AI, large-scale batch jobs, and data-intensive applications. The team is arguably one of the most technically impressive on this list — it includes the creators of Luigi and Seaborn, as well as olympiad medalists. At ~110 employees, Modal practices deep work culture with minimal meetings and maximum engineering autonomy. The company contributes meaningfully to the open source ecosystem and builds developer tools that prioritize correctness and performance over hype.
7. Replit
Replit is building the future of software development with an AI-powered online IDE that makes coding accessible to everyone. The platform itself is built on open source foundations, and the company's AI agent can generate full applications from natural language prompts. At ~200 employees, Replit combines the energy of a developer tools startup with genuine product impact — millions of people use the platform to learn, build, and deploy software. The 3.9 WLB score is solid for a ship-fast culture, though some reviewers note that operations can feel disorganized.
8. Vercel
Vercel is the company behind Next.js, one of the most popular web frameworks in the world. They also maintain Turbopack, the AI SDK, and a growing suite of open source tools that power the modern web. At ~600 employees, Vercel is the second-largest company on this list and operates with the intensity of a company half its size. The engineering culture is world-class — if you work on Next.js or Turbopack, your code ships to millions of production applications. The trade-off is clear from the 3.4 WLB score: high expectations and a relentless shipping cadence mean long hours are common.
9. Hugging Face
Hugging Face is the GitHub of machine learning — the platform where the entire AI community shares models, datasets, and Spaces. The Transformers library alone has over 130,000 stars on GitHub and is used by virtually every ML team on the planet. At ~400 employees, Hugging Face has true open source DNA: flat hierarchy, remote-first, flexible hours, and a culture of transparency. The 4.1 WLB score is the second-highest on this list, reflecting a team that protects boundaries. The main trade-off? Compensation is below FAANG levels, which is the price of working at a mission-driven open source company.
What to Look For in Open Source Companies
Not all open source is created equal. Some companies release a CLI tool on GitHub and call themselves "open source." Others build their entire business on code that anyone can inspect, fork, and contribute to. When you're evaluating an open source company, here are the questions that separate the real thing from the marketing:
- Is the open source work core to the business, or a side project? At companies like Hugging Face and LangChain, the open source project is the product. At others, it's a community goodwill effort that sits apart from the revenue-generating work. Both models can be good places to work, but the experience is very different.
- Does the company contribute upstream, or just consume? Companies that contribute back to the libraries and frameworks they depend on are signaling a deeper commitment to the ecosystem. Ask during interviews about their contribution policy.
- Are engineers encouraged to maintain OSS during work hours? Some companies list "open source" as a value but expect that contribution happens on personal time. The best open source companies treat OSS maintenance as part of the job, not a side hustle.
- Does the culture genuinely value transparency, or is it marketing? Open source culture should extend beyond the codebase. Look for transparent compensation bands, public roadmaps, open decision-making processes, and a willingness to discuss failures publicly. If the code is open but the culture is closed, that's a red flag.
The 9 companies on this list all score well on these criteria, though the degree varies. Weaviate and Hugging Face are probably the most "open source to the core" in terms of both product and culture. Vercel and Airbnb are companies with massive open source contributions but commercial products that go well beyond the OSS layer. All of them offer engineers the chance to work on code that reaches far beyond a single company's walls.
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