Nyxcipher | CTO | USA, Kansas | Remote

We are seeking a skilled and motivated developer to join our team for the next phase of our project. The project is currently in progress, with 30% of the Minimum Viable Product (MVP) already completed in Version 1. The focus now shifts to Version 2, where we need to implement additional functionalities, fix bugs, and prepare for the development of smart contracts by the end of this year.

Project Details: Total Salary Budget: $150,000 - $180,000 USD (Hourly Rate: $100 - $130 USD, paid via PayPal or Wise) Timeline: The development must be completed by December 2025. This includes both web and smart contract development. After this phase, we plan to launch a mobile version of the platform.

Key Technologies: Node.js MongoDB Solidity Smart Contracts Web3

Requirements: English proficiency is essential for effective communication with the team. Strong experience with the listed technologies is required. Agile or Scrum methodologies are used, with collaboration tools such as Jira and GitHub. The project includes a collaborative development team, and there will be regular team meetings twice a week. Flexibility for time zone differences will be necessary.

Additional Information: There will be learning opportunities for technologies you may not be fully familiar with. Collaboration and communication within the team are key to our success, and you will work closely with other developers to achieve project milestones.

Contact: Email

Email is hidden

Optimal | London, UK | ONSITE

AI Simulation and Control Engineer: Up to £150k + 2% depending on experience (https://wellfound.com/l/2aus7a)

Full-Stack Software Engineer (Python): Up to £150k + 2% depending on experience (reach out direct to Email is hidden)

Optimal builds AI agents to control the world’s critical infrastructure - from factories, to datacenters, to farms.

We are backed by the Director of AI Research at Google DeepMind as well as early VC investors in SpaceX, Anduril, and Palantir.

We have built the world’s most advanced AI control system for high-tech greenhouses and have just signed out first customer contracts in North America and Europe having proven the performance of our AI across 3 seasons in our own demonstration greenhouse.

Email is hidden

https://www.optimal.ag

Beautiful.ai | Full-Time | Remote in US & CAN | SaaS B2B Presentation Software | Series B | 16M Funding | AI Industry

1. Senior Manager, Software Engineering | 200k - 250k Base Salary + Equity | https://boards.greenhouse.io/beautifulai/jobs/4634347007

2. Accounting Manager | 100k - 120k Base Salary + Equity | https://boards.greenhouse.io/beautifulai/jobs/4619672007

3. Senior Product Marketing Manager | 120k - 150k Base Salary + Equity | https://boards.greenhouse.io/beautifulai/jobs/4617650007

4. Senior Lifecycle Marketing Manager | 120k - 150k Base Salary + Equity | https://boards.greenhouse.io/beautifulai/jobs/4588688007

5. Head of Enterprise Revenue & Go-To-Market | 225k - 250k Base Salary + Equity | https://boards.greenhouse.io/beautifulai/jobs/4622705007

Rechat | API Engineer & More | Remote

Rechat is the leading AI-powered operating platform for real estate brokers and agents. Think Shopify for real estate—a mobile-first super app with marketing automation, workflow management, and everything agents and brokers need to run their business in one place. We’re a small, sharp team building a big, sophisticated product without the usual corporate nonsense.

Why You’ll Like It Here:

Remote-first with flexible hours Minimal meetings—we focus on real work No tech hype-chasing—we use the right tools, not the latest trends Flat team structure—no layers of bureaucracy Who We’re Looking For:

Senior Frontend Engineer (TypeScript, React) – Own the UI and craft intuitive experiences Senior Backend Engineer (Node.js, PostgreSQL) – Build and refine our robust, high-performance backend If you thrive in small teams solving big technical challenges, reach out to Email is hidden.

AVAYL | Full-Stack Engineer | Onsite (Berlin) | Full-Time | avayl.tech

We're transforming Medical Information in life sciences with AI-driven solutions, enabling companies to keep pace with evidence generation and optimize interactions with healthcare professionals and patients. Backed by VCs and unicorn founders, we're building the next generation of tools to modernize how medical information is managed and delivered.

We're looking for a highly skilled and passionate Full-Stack Developer to join our engineering team. In this role, you will be instrumental in building and scaling our AI-native SaaS (Vue.js/Flask/MongoDB), working closely with our co-founder and CTO.

Apply here https://www.avayl.tech/jobs/fullstack or email us at Email is hidden

Upstream (YC S23) | Founding Engineers (mobile, product) | Full-Time | ONSITE | Paris | €75K-€100K

We went through YC and raised a $3 million pre-seed round from amazing investors.

Upstream is a modern email client that lets teammates communicate with efficiency and ease. In a world dominated by Slack, where chit-chat never stops, we believe that teams deserve a tool that lets them create the structure and organization that make them productive.

As a founding engineer at Upstream, you’ll play a fundamental role in shaping the company and the product. This role will be primarily hands-on building.

Founding Mobile Engineer:

- Develop React Native iOS and Android apps that are efficient, reliable, and optimized

- Take the app from a concept, to a prototype, and ultimately to production-ready software, and ship it to lots of people

Founding Product Engineer:

- Develop a fast & reliable email application across mobile and web

- Build production-ready software, and ship it to lots of people

- Be pragmatic in determining which tech investments to make now versus later

Apply here https://www.ycombinator.com/companies/upstream

ALT | Remote (EU) | Full-time | Frontend Software Engineer

We're a small, established company specialising in subsurface instrumentation development, as well as the software needed to handle subsurface data. As of right now, we're working on a product to streamline management, delivery and visualisation of data.

Currently chasing a frontend developer with a flair for UI/UX design, and experience in Vue.js and D3. Must have a strong mathematical background.

Open to employing via company-of-record (such as remote.com), or direct B2B consulting. If you're in Luxembourg, we can employ you directly. Reach out to me at jobs <at> alt.lu.

Klara Inc | Fully Remote | Global | Full-time Contract Developer

Klara Inc (klarasystems.com) provides development & solutions focused on open source software and the community-driven development of OpenZFS and FreeBSD. We develop new features, investigate/fix bugs, and support the community of these important open source infrastructure projects. Some of our recent work includes major ZFS features such as Linux Containers support (OpenZFS 2.2: https://github.com/openzfs/zfs/pull/12263), and Fast Deduplication (OpenZFS 2.3: https://github.com/openzfs/zfs/discussions/15896).

We successfully hired from HN in the last round and are looking for more OpenZFS Developers (3+ years of experience) to join our team!

- Strong skills with Kernel C programming and data structures

- Experience with file systems, VFS, and related operating system concepts (threading, synchronization primitives/locking)

- Awareness of ZFS (MOS, DMU, ZPL, pooled storage, datasets, vdevs, boot environments, etc) concepts.

You can submit an application on our website: https://klarasystems.com/careers/openzfs-developer/

If you'd rather talk to us via e-mail, just drop us a line at Email is hidden.

Promptfoo | Multiple Roles | Remote US (HQ: San Mateo, CA)

About us:

Promptfoo builds the leading open-source framework for LLM security and evaluation. Our tools help over 50,000 developers test and secure AI applications. Backed by a16z and led by YC alumni, we are shaping the future of AI safety.

Open Roles:

- Staff Engineers

- Research Engineers

- Developer Relations

How to apply:

- Try Promptfoo at <https://promptfoo.dev>

- Review our code at <https://github.com/promptfoo/promptfoo>

- Email Email is hidden with "HN" in the subject, your GitHub/LinkedIn, and a brief note on why you're excited about our work.

Join us in building safer, more reliable AI.

Extend | Senior/Staff Software Engineer | NYC | Full-time | | $175k-$250k | 0.50% - 1% Equity

Extend is building a next generation document processing platform (massive market w/ low NPS existing solutions) (https://extend.app/)

Apply here: https://jobs.ashbyhq.com/extend/9d4d8974-bd9b-432d-84ec-8268...

--------

Why you should consider joining:

- We're looking for engineer #3, lots of equity, culture of high impact and ownership, in-person in NYC

- We've accelerated revenue 15x this past year to 7-figures in ARR

- Our customers include companies like Chime, Flatiron Health, Brex, Opendoor, Checkr, and many more

- We're supporting customer and revenue metrics with 1/2 the team size of other startups, so everyone joining at this stage will have outsized impact

- Backed by YC, Homebrew, investors from OpenAI, and more