Contra’s Project Cost Calculator blends data from labour industry reports and with internal project statistics to help people make informed hiring decisions.

I was brought on as a back-end developer to create APIs to power the Calculator front-end being developed by Unseen.

After aligning on requirements and success criteria with internal stakeholders, I began by reviewing and building an understanding of the underlying data prepared by the data analyst.

• Private APIs for the front-end to query cost calculations based on different worker criteria

• Capturing lead registrations

• Adding an email template to be sent to new leads

• Integrating our solutions with existing marketing and application monitoring pipelines

To minimize revisions, I reviewed the existing codebase and discussed internal coding styles and best practices with Contra’s team. This approach helped inform my solutions, allowed me stay consistent with their patterns, and ultimately prevented revisions.

Next, I used dbdiagram.io to sketch potential database structures. These visual representations formed the basis for detailed discussions with Contra’s internal developer team, helping us evaluate different approaches and quickly agree on a final solution.

Once the database structure was defined, I followed a similar process to outline, propose, and refine the API to be used by the Calculator client.

With both the database schema and APIs agreed upon, I was able to share the expected schemas and API signatures with the front-end team.

This removed me as the bottleneck, and allowed them to work in parallel, in turn reducing the overall project timeline.

I created scripts for taking data from Google sheets, converting into PostgreSQL compatible structure, and running tests to verify calculations prior to import.

This allowed us to refine and update the calculations as more data was prepared.

Lastly, the back-end implementation itself consisted of:

Documenting and running database migrations

Creating GraphQL endpoints (and corresponding tests) with Apollo

• Adding a new email template for lead follow-up

• Seamlessly connecting these pieces within Contra’s existing architecture

From start to finish, the back-end work took around three weeks of asynchronous work.

You can interact with the Calculator, and the API I build powering it, at this link.