John Ostrowski ๐Ÿ”Ž๐Ÿ“ˆ๐Ÿ’ฐ

Dir. Product & Experimentation | I help you prioritize, build, and communicate with confidence.

Wrocล‚aw, Poland (+01:00 UTC) Portuguese, Englishfrom Curitiba, Brazil
Usually responds in 2 days
Free
Price per hour
Not available
Time Blocks Available
5.00
122 reviews / 218 sessions
-
-
Next availability
Not available in the next 30 days

I had my first session with John who is a fantastic mentor, with a wealth of knowledge in the CRO space. John was so well prepared, asking a few pre-screening questions ahead to help maximise our time. The slides and material shared during our session were the perfect foundation for me to start thinking about how best to frame and educate my organisation about what โ€œCROโ€ is and the different ways that my squad can support the different teams and streams of work within the business. Looking forward to another session soon!

Karla Sumera

John didnt hold back, a generous mentor with practical and precise tips and advice. I'm much more aware of how to improve my data collection, proper tracking approach, and visualization. one of my most humbling sessions on the platform, I highly recommend John!

Apo Zadeh

Just had another brilliant session with John. Really appreciate your energy and ability to provide so much guidance and insight within such a short period of time. In both conversations, John has really done a great job at understanding my challenges and what I'm trying to achieve to then provide excellent recommendations. An all-around super helpful call which has left me feeling optimistic and ready to smash the challenge.

Hamel Shah

Bio

Hello from somewhere around the world โ˜•๏ธ After 200 sessions, I've been most successful in helping people optimize experiences, understand, prioritize, and test before they invest. Build the right thing, then build the thing right. On the video: 0:25 โ€”ย Why I'm in Growth Mentor 1:02 โ€”ย How do I help you? 1:48 โ€”ย The GROW framework I use during calls 2:26 โ€”ย Specific themes I helped mentees with

Expertise


  • Building a team

    I hired and structured the first Growth/CRO cross-functional team to replace CRE (Conversion Rate Experts agency) for Brainly throughout their expansion phase from 300 to 400 Million Active Users (MAUs). From Beyond Entrepreneurship 2.0, I'll remind you of the most important business metric that's often forgotten on executive meetings, what's the percentage of key seats you have filled with the right people in your organization.

  • Conversion rate optimisation

    I built the early stage of my career on data analytics, AB testing, user research, and project management, the building blocks of conversion optimization. If you are a founder willing to evolve testing because you believe in the aggregation of marginal gains, an investor running due diligence on a new acquisition prospect, an agency Head Of that offers conversion services, a specialist looking for tactical and method advice โ€”ย I can mentor and share personal first hand experience with you.

  • Design / UX

    After moving to Product, I worked closely with product designers and art directors. Those experiences honed my intuition for great design, UI solutions, component work, interactions, and user experience. After many hours of Balsamiq napkin sketch and Maze tests, if you're looking for design critique, optimizing existing experiences from 1 to 100, or a leader creating net new experiences from 0 to 1 โ€”ย I can mentor and share first-hand experience.

  • Product management

    I covered a lot of mileage in all things Reforge and had the privilege to learn from very experienced Product VPs along the journey. Mentees often bring questions on product rituals, artifacts, and ways of working cross-functionally to master shaping the product, shipping the product, and syncing the people.

  • User research

    My career grew with a UX flavor after going through Reforge's User Insights for Product Development program. I got to chance to work and learn from Sr. researchers from Slack and Facebook. At Money.ca I had the pleasure of working with Mindberry on a year-long research discovery program that started our continuous discovery practice. If you are looking for design/prototype critique, trying to design a usability test for a relevant decision โ€”ย I can mentor and share personal experience.

Toolkit


  • Obsidian logo

    Obsidian

    5 years of experience

    I'm a power user of obsidian and received positive community feedback from my capturing system. I use multiple advanced features and maintain an Obsidian Publish as my open knowledge base for the community. Check it here https://positive-experiments.com/KnowledgeBase/Content/Capturing+systems

  • Ahrefs logo

    Ahrefs

    9 years of experience

    Audit the technical SEO side of your website, understand the performance of your organic traffic efforts, study content and keyword gaps to move faster than the competition. I'm happy to support you with ahrefs!

  • Asana logo

    Asana

    8 years of experience

    Delegate and manage with confidence following a strong and repeatable process. Project management is where I'm able to add the most from my engineering background to the marketing world.

  • Google Analytics logo

    Google Analytics

    11 years of experience

    Google Analytics is a lovely platform but harmful to your decision making when set up wrongly. Count on me for supporting your analytics health-check, setting goals and funnels. GA is my bread and butter for conversion research.

  • Google Analytics Experiments logo

    Google Analytics Experiments

    8 years of experience

    Move faster than your competition by testing more, failing fast, and validating what you learn from personas. We use Google Optimize, powerful yet a free tool, to make the magic happen.

  • Google Data Studio logo

    Google Data Studio

    9 years of experience

    I'm an enthusiast of storytelling with data. Data Studio will help us to power not only great-looking dashboards but interactive analysis that tells your team a growth story.

  • Google Tag Manager logo

    Google Tag Manager

    9 years of experience

    My favorite tool. I worked on multiple tracking plans to support PPC teams with conversion tracking, behavior data (events) for better remarketing, automation, and funnel mapping. Tag Manager allows us to learn from user's interactions without messing with coding.

  • Google Webmaster Tools logo

    Google Webmaster Tools

    9 years of experience

    Understand the very technical side of SEO, organic coverage, robots.txt and so on. In Search Console, I use a framework to boost your organic clickthrough rate on important pages based on Google SERP position benchmarks. I worked a lot with the platform when I supported the migration of a Hungarian eCommerce to a Shopify Plus account.

  • Hotjar logo

    Hotjar

    8 years of experience

    Both Hotjar and SessionCam are my go-to qualitative tools for understanding the first level of WHY something is happening after we see WHAT is happening (from data tools). Heatmaps and recordings with auto taggings are my bread and butter to QA experiments in production, analyse behavior in particular funnel segments and all that jazz.

  • JIRA logo

    JIRA

    7 years of experience

    Extensive use of Jira Product Discovery and Jira Cloud for all things Product Management and delivery sprints. Ran countless backlog refinements, sprint plannings, and product roadmap.

  • Supermetrics logo

    Supermetrics

    7 years of experience

    Connected multiple sources using Facebook Ads, Google Ads, and Shopify connectors (for Shopify Revenue and AOV true value) for a single source of truth Google Data Studio dashboard for Shopify Plus accounts

Industries


  • Financial Services

    Product and experimentation growing Canadaโ€™s #1 destination for everything Money. I continue to dig deep into dominating SERPs for massive keywords and building comparison products for users to find the right partners to work with.

  • EdTech

    ๐Ÿ† 2020 Growth Awards with Brainly (450M MAU) by expanding their mobile app reach and becoming #1 across 6 Geos. Worked on Product Retention with the most experienced team in the company, and led experimentation across multiple areas as Sr. Analyst. Jumped to Conversion Manager where I led conversion to free-trial and web to app downloads.

  • Affiliate Marketing

    Worked with massive website networks that owned areas of the internet via SEM and monetized through affiliate links at scale across different platforms.

  • E-Commerce

    Worked with Shopify Plus migrations and managed conversion rate optimization for multiple stores. I also opened my e-commerce as a side hobby so I understand the basics of operations and empathize with small business struggles.

Experience

  • Ladder.io

    Head of CRO
    โ€ขtry.ladder.io/

    As Head of CRO, I oversee client communication, expectation management by setting goals to conversion programs, and quality of execution. My time is split on training, reinforcing our research process, improving client's strategy, and execution - I really enjoy crafting testing hypothesis and the prioritization talk (:

    Digital Agencies
  • Wise Publishing

    Director of Product and Experimentation
    โ€ขwisepublishing.com/

    Mortgage for the first home, insurance for loved pets, braving the stock market, diversifying with alternative investments, orchestrating a comfortable retirement ๐Ÿ’ธ Financial decisions and life milestones we all go through. Moneywise.com and Money.ca lead the industry offering comparison experiences for each pivotal moment, helping individuals to find the right financial products for their journey. โ€” My current time split: 40% โ€” Expanding product categories across US and CA with joyful reading experiences. 25% โ€” Managing the experimentation backlog of our optimization pod (in-house specialist + 2 agencies) to extract all the juice worth the squeeze from commercial areas. 20% โ€” Building our commercial data platform back end to nail compliance 15% โ€” Maturing our product development process, aligning to delivery process, emphasising compliance and legal needs. โˆž โ€” Energising teams, spreading positivity, and good karma. Skills and technologies: Google Analytics 4 | Big Query | Looker | SiteSpect | Hotjar | Applied Statistics for AB testing | Tableau | User testing | SemRush | Ahrefs | Jira | Notion

ยฉ 2026 Growth Tonic LLC. All rights reserved.
Made within Glyfada