Helping small business owners getting paid faster

Vendas for iOS was designed to empower business owners, making it easy and fun to keep their sales, clients and inventory updated and accesible all the time.

  • Client


  • My role

    Team lead, Product management, User research, UI Design, Prototyping, Illustration

  • Visit

    App Store

  • Project date


  • Working on this app from concept to app store launch was an amazing experience to me. I had the chance to work with amazing talented people that acted as a trully startup inside a larger company.

  • What went right

    Lean approach helped us move fast and test our hipothesys on the go.

  • What went wrong

    Some technical decisions such as integrating some parts of the app with legacy code have slowed us down considerably. A more reliable estimate and playing in a safer zone regarding external integrations would have given us a better timing.

Design process

Using lean methodology to deliver the best product

From start we designed a workflow and for the project that would make us move faster and not wasting time on wrong assumptions.

We started defining some business needs and problems that we could solve with the app. Then ideating initial ideas and validating some of those with potential clients. Once we reached to one idea that seemed good enough from the user and business perspective we begin to wireframe some concepts. From that we built a prototype that'd allow us to test the concept both internally and with some external users. After some rounds of changes we moved to build a working version.

We didn't know the caveats of working with Apple's app store, so we wanted to release a very simple early version just to measure how often we'd be able to release new versions. Also with the app available at the store we could automate the testing process and start collecting metrics. We then spent a lot of time tweaking the app, launching new versions and analizing metrics for the next iterations.

Team building

A different challenge

We named our team 'Mobi Dicks'

Building the right team was the key to the success we have with the app. Our team consisted on 1 mobile developer, 2 back-end developers (after having integrations problems we moved from 1 to 2 back-end devs), 1 quality assurance professional and me working as a product manager and UI/UX designer.

An important aspect of the entire project for me was learning a lot about team building and how to make everyone work with a real purpose. Also dealing with conflicts, problems and everything that comes along with working with talented people. There were times that I'd just want to sit down and design stuff, but I felt the responsibility of making a good environment for everyone to work on and also making sure that the company board and partners were happy with the results.

There was the pressure of actually delivering a quality product for our users. They didn't care about our problems and how hard it was to build some feature, they just wanted to have a good experience and also having a good support in case they had any problems. And that's where having a connected team helped. I tried to show them how important it was for us to build the best product we could and how many lives we could help with that. They really embraced that and worked together to deliver much more than we initially expected.

App icons

Designing the right icon in more than an aesthetic choice, it can make a huge difference on the download metrics

V2 Study
V2 Study
V2 Study
V2 Study
V2 Final


Exploring interactions

Visual Design

Playing with color and shapes to design a beautiful experience

Early study - Dashboard
Early study - Invoices blank
Early study - Invoice list
Early study - Animation
Final version - Dashboard
Final version - Invoice list
Final version - Installments
Final version - Client

Blank state illustrations

Empty screens don't have to be boring


Streamlining user flows

Making it simple

Although the app was very simple, to get to that simplicity was not an easy task. We had to redesign the first time experience many times to deal with very low user activation rates (people creating accounts). And later improving the invoice flows since we had a super low user engagement numbers (people got in but didn't use the product). Streamlining the user flows was very important to make sure the main tasks could be done within just a few taps.

Sign up and onboarding quiz
Making first invoice
Sharing invoice

App Store Reviews

It's all about the customers

Very good

"Wonderfull app, easy to use and very helpful for everyone who works with sales, and if you have any questions there’s even a chat. The response is really fast! 👏🏾👏🏾👏🏾"

Great app

"Excellent app, dynamic, complete and instructive. The most interesting part is that there’s an open communication (chat) between users and developers. With users’ opinions, the app can become much more powerful"

Extremely practical

"I never imagined that taking control of my invoices could be so easy! I can make, share and follow my invoices from anywhere! For sure it’s a big business booster!"

Great application

"I’m loving it! I now can have some much control of my invoices."

A great start

"I liked the usability, it’s much more fluid than the other apps I’ve seen. Of course there’s a lot of improvements to be done, by I’m sure that the always available team is working constantly to meet all user needs."


"Very good app! Light weight, practical and easy to use. The best one in it’s category. I’m a writer and I use the tools to manage my book selling invoices. Perfect for what I need."


From the initial release on March 30th, 2015 to the the time I left the company at August 2016 the app had 19,000 downloads (that number is around 50,000 now at October 2017). 94% of that number is from Brazil and the rest is splitted across over 30 different countries. The number of new accounts created through the app was around 10,000, from which ContaAzul's marketing and sales team have been working to qualify them as leads and to make them potential ContaAzul paying customers. Although the app was always free, it was pretty clear that it have become a great source of qualified leads and it also generated an unmesurable brand awarness and promoted the company as innovative and truly user centered.

The app reached top 5 in Brazil's business category in 3 different occasions
Each new release represented a spike at the download numbers. That shows the importance of releasing stable and reliable versions.

Cherry picked projects 🍒

I have worked with all kinds of projects ranging from full product designs to icons and illustrations. This is a small selection of some very recent work I've done.

You'll love working with me

Don't take just my words for it!

"Guilherme is, hands-down, the most talented designer I have ever met. His sensitiveness, good taste and eye for details are just the tip of the iceberg of good things I could say about him. He is also am impressive illustrator. From comic strips, to icons, to full-featured user interfaces, he always creates amazing solutions. His comprehensive knowledge in user experience and usability; skills in HTML, CSS and JS coding makes him a unique front-end developer. I just feel blessed having him as a friend and working partner. "
Vinicius Horewicz
Software craftsman @ Infinity Health
"It’s rare that you come across a standout talent like Guilherme. Guilherme worked out of Brazil as a contractor for our design team in Sydney. The first thing I noticed about Guilherme are his unparalleled design skills. It was also inspiring to see Guilherme tackling each challenge he was given with enthusiasm and to make the impossible possible. Guilherme is a very pleasant person to work with, has a good sense of humour and integrated very well in our team and workflows. Guilherme would be a true asset for any positions requiring a senior designer and comes with my heartfelt recommendation. "
Michael Imstepf
CTO @ Artesian
"By all means. Guilherme Simões did a fantastic job. We have commissioned him to design two short videos for our design marketplace PicWood. But it´s not only the result that impressed us. It was also the working process that made it so easy to work with Guilherme. The communication was smooth, the delivery fast and the creativity exchange fun. - AAA rating! "
Stephan Doesinger
Founder/CEO @ Styliamo
"Quality of work delivered speaks for itself. Creativity and support excellent! Personal and friendly approach all the way through. Will definitely use his service again! "
Data Solution Architect @ Microsoft
"I worked with Guilherme to design a set of landing pages and ad units to be A/B tested for my B2B software client. Guilherme studied and understood the wireframes, style guide, offer, and test hypotheses to create beautiful, communicative, and convincing compositions. He has a positive attitude, clear communication, and his designs were detailed, polished, and professional. He designed multiple versions of the pages to test layout and messaging hypotheses. I'm certain that these pages will result in improved conversion rates and happier customers for my client. I would be happy to hire Guilherme again for UX, landing pages, ad units, logos, or print design work. A+ work! "
Dan Kuthy
CEO @ Measured Growth