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OS Domains
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Engineering and operations at a boring, profitable company.

We have been operating since 2008, profitable since 2014, self-funded throughout. We hire 3-5 people per year and we plan to keep that pace. We are a small team in Vienna, with a remote presence in Berlin, Lisbon, and São Paulo. We do not pitch hyper-growth and we do not pitch lottery-ticket equity. What we offer instead is the chance to operate real infrastructure that real customers depend on, learn from people who have been doing this for 15+ years, and not get laid off in three months when a VC pulls funding because we do not have VC funding.

See the 5 open roles →
At a glance
Headcount
22
Open roles
5
Office
Vienna
Remote OK
EU + LATAM
Funding
Bootstrapped
Avg tenure
4.3 yrs
How we work

Six principles, in order of how much we mean them.

These are not aspirational. They describe how we already work. If they sound exciting, this might be a fit. If they sound boring, this almost certainly is not.

01

Boring beats clever

We pick the boring technology that we can operate at 3am. Customers do not care that we use the latest framework; they care that mail is delivered.

02

Operators on call

The engineer who built the feature is the engineer who fixes it at 4am. No throw-it-over-the-wall to a tier-1 support team. Customer impact is your problem.

03

Write things down

Every architectural decision, every postmortem, every customer escalation has a written record. Verbal-only decisions get re-litigated; written ones get refined.

04

No commission

Nobody is on commission. Sales, customer success, CSMs — all salary-plus-retention. This shapes what we do and do not pitch to customers.

05

Bootstrapped time horizon

We have been profitable since 2014 and plan to still be here in 2034. That changes what we say yes to and what we say no to versus a VC-backed team.

06

Honest RCAs

When something breaks, we publish the root cause within 48 hours without softening the language. Customers and competitors both read those RCAs; we do not soften for either audience.

Open positions · 5 roles

What we are hiring for right now.

Salary ranges are real and posted on every role per Austrian transparency standards and our own preference. Where we cannot meet your stated expectation we will tell you on the screening call, not in week 6 of the process. If your role is not listed but you think we should hire you, write to [email protected] with a specific pitch.

01

Senior Backend Engineer · MTA Platform

Engineering · Vienna or remote (EU) · Full-time · permanent · €85,000 – €115,000 base + retention bonus

You will own the KumoMTA-based outbound platform that delivers hundreds of millions of messages per month across 7 PoPs. Day-to-day mixes Rust development (KumoMTA core extensions), Lua scripting (per-customer policies), Postgres performance tuning, and on-call rotation. We are not hiring you to "modernize" anything — the platform works. We are hiring you to make it faster, observable, and predictable under load.

What you need

  • 5+ years backend at production scale (preferably with messaging, queueing, or networking)
  • Comfort with Rust, Lua, or willingness to learn both quickly
  • Strong Postgres or comparable RDBMS experience including index design and query planning
  • Experience operating a system you have built — not just shipping features over the wall
  • EU work authorization or willingness to relocate to Vienna

Nice to have

  • PowerMTA, KumoMTA, Postfix, or other MTA experience
  • BGP routing or ASN-level networking exposure
  • Open source contributions you can point to
  • German conversational (not required; team default is English)
Apply for this role →
02

Deliverability Operations Engineer

Deliverability · Vienna, Lisbon, or Berlin · Full-time · permanent · €72,000 – €95,000 base + retention bonus

You will run the daily operational rhythm of our deliverability program: monitoring inbox-placement metrics from synthetic probes, investigating reputation anomalies, escalating to mailbox-provider postmasters, and tuning our IP-warming scheduler based on what we learn. This is the role where you become the team that operators of email infrastructure quote at conferences.

What you need

  • 3+ years hands-on deliverability work at a high-volume ESP, ISP, or comparable
  • Operating relationships with Gmail, Outlook, Yahoo postmaster teams
  • Comfort reading SMTP logs, DMARC reports, and bounce classifications
  • Strong written communication for customer-facing RCAs

Nice to have

  • Experience running automated reputation monitoring at scale
  • Postmaster Tools and SNDS deep familiarity
  • BIMI/VMC configuration experience
Apply for this role →
03

Customer Success Engineer (Enterprise)

Customer Success · Vienna or remote (EU) · Full-time · permanent · €68,000 – €88,000 base + retention bonus

You will own a portfolio of 8-12 Enterprise customers, attend their quarterly business reviews, lead architecture conversations with their engineering teams, and escalate to OS Domains engineering when product changes are required. You are technical enough to debug an SMTP handshake with a customer's ops team, business-fluent enough to brief their CTO on the migration roadmap. Not a salesperson — we do not give CSMs commission on expansion.

What you need

  • 3+ years customer-facing technical role at a B2B infrastructure company
  • Strong technical communication in English; second EU language a plus
  • Comfort in customer war rooms during live incidents
  • EU work authorization

Nice to have

  • Email infrastructure or deliverability background
  • Experience with Enterprise procurement processes (DPA negotiations, security questionnaires)
Apply for this role →
04

Senior SRE · Multi-PoP Operations

Engineering · Vienna or remote (EU) · Full-time · permanent · €80,000 – €110,000 base + retention bonus + on-call premium

You will own the cross-PoP operational layer: BGP and DNS, capacity planning, the public status page automation, on-call response, the postmortem culture. We have 7 PoPs, 14 production services, an external SLA we honor, and a public status page where every incident gets a written RCA within 48 hours. Your work is the difference between us hitting that SLA and not.

What you need

  • 5+ years SRE/Operations at production scale
  • Strong networking fundamentals (BGP, anycast, multi-region failover)
  • On-call experience and demonstrated handling of customer-facing incidents
  • Linux internals fluency (systemd, eBPF, Prometheus stack)

Nice to have

  • Multi-datacenter operations including BGP route policies
  • Experience writing public RCAs that customers and competitors take seriously
Apply for this role →
05

Junior Backend Engineer

Engineering · Vienna (in-office for first 12 months) · Full-time · permanent · €50,000 – €62,000 base + retention bonus

You are 1-3 years into your career and want to learn from operators who have been doing this since 2008. You will pair-program for the first 6 months, ship to production by week 4, and own a feature end-to-end by month 9. Vienna in-office is required for the first year because mentorship works better when you can see the screen across the desk.

What you need

  • 1-3 years professional software engineering
  • Strong fundamentals in any compiled language (Rust, Go, Java, C++, C#)
  • A side project or open-source contribution you can walk us through
  • Willing to relocate to Vienna or already there

Nice to have

  • University-level CS background (not required; bootcamp + side projects is fine)
  • Prior interest in mail systems, networking, or distributed systems
Apply for this role →
Compensation and benefits

Twelve specifics, in plain numbers.

Most company "perks" pages are vague paragraphs about "competitive compensation" and "great culture." Below is what we actually offer, with numbers wherever possible. If something here turns out to be inaccurate or stale, email [email protected] and we will fix it.

Compensation

Base salary (not commission-based) with an annual retention bonus paid on the anniversary of your start date, scaled to tenure. Salary bands are published internally and revisit annually.

Equity

We are bootstrapped and not on a venture path. No share options. We compensate by paying market base salaries and being honest about the upside being career growth, not lottery-ticket equity.

Vacation

28 days of paid vacation per year (Austria minimum is 25; we add 3). Plus 13 Austrian public holidays. We close between Christmas and New Year on top of that.

Sick leave

Unlimited paid sick leave with no documentation required for under 5 days. We do not track it; we trust you.

Parental leave

6 months fully paid for the primary caregiver, 3 months fully paid for the secondary caregiver, on top of statutory Austrian parental leave. We have hired back every parent who took it.

Remote work

Remote-friendly within EU and LATAM time zones for senior roles. Junior roles require Vienna in-office for the first 12 months. Hybrid (2-3 days office) is also available.

Office stipend

€600/year toward home office equipment. €100/month toward your mobile and home internet bills.

Health

Austrian statutory health insurance covers most things. We additionally cover a private health top-up that gives faster specialist access (~€100/month).

Learning

€1,500/year per person for conferences, courses, books. No approval process beyond a Slack message.

On-call premium

Engineers on the rotation receive a €450/month on-call stipend for ~1 week in 6. Page during off-hours triggers comp time the following week.

Lunch

Catered lunch at the Vienna office Monday through Thursday. Friday is "go explore Vienna" day.

Sabbatical

After 5 years with us, 1 paid month off. After 10 years, 3 paid months off. Two team members have taken sabbaticals so far; both came back.

Hiring process

Seven steps. End-to-end in 3-5 weeks for most candidates.

  1. 01

    Application

    CV + a short note explaining why this role specifically. No cover letter required. We respond within 5 business days, even if it is a "no thanks."

  2. 02

    Recruiter screen

    30 minutes with our People Ops lead. Logistics check (compensation expectations, location, work authorization) and a chance for you to ask anything about the team or company.

  3. 03

    Hiring manager call

    45 minutes with the team lead. Technical/role-specific discussion. We talk about the system you would be working on, the problems you would be tackling, and your background. Bidirectional — you should leave with a clear sense of whether the role excites you.

  4. 04

    Take-home or live coding

    For engineering: a 3-4 hour take-home that resembles work we actually do (typically a small SMTP-related service, a queue-handling problem, or a Postgres performance scenario). We pay €200 for completed take-homes regardless of outcome. For non-engineering: a structured case discussion instead.

  5. 05

    Team interviews

    Two or three 45-minute conversations with future colleagues. We deliberately schedule these on the same day or two adjacent days so you do not lose a week. Includes one peer-level interview where you ask them what working here is actually like, with no manager present.

  6. 06

    Founder/CEO conversation

    For senior roles, a 30-minute call with our founder. For junior roles, a 15-minute "welcome and questions" call after the offer.

  7. 07

    Reference checks and offer

    We call 2-3 references you provide. Offer goes out within 3 business days of completing the loop. Offers are negotiable on details; we will not chase you with 5 follow-up emails.

Apply or ask

Send your CV to [email protected]. We respond within 5 business days.

No long application forms, no AI screening tools, no automated rejections. A human reads your CV. If you are a fit, we say yes; if you are not, we say no with a short reason. Either way you hear back within a week. For roles not listed, pitch us in 3-4 sentences why we should create one.

Phone +43 1 205 11 80 Mon–Fri · 9–18 CET
Email [email protected] Avg response 4h business
Office Fleischmarkt 1, 1010 Wien By appointment