Development of the backend for the Synastry Chart PDF generator

On one of our websites, there is targeted traffic in the horoscope and compatibility forecast niche (USA GEO). To monetize this traffic, we planned a partnership with a service that generates similar reports (see PDF attachment). However, since we have already implemented a number of generators and SaaS ourselves, the idea arose to create our own product that would meet our specific requirements. And that we could connect to our other traffic sources in the future. 

At this moment, all our developers are busy with other projects, so we are looking for a talented freelancer for long-term collaboration on this project.

Task Description:

Develop a backend for a PDF report generator of the Synastry Chart type, which will operate according to the following logic:

1. Connection to the astrological library:

   • Use Swiss Ephemeris (https://github.com/arturania/swisseph) or similar tools to calculate the positions of the planets.

2. Calculation of planetary positions:

   • Based on the input data (date, time, place of birth) filled in by the client through a form on the website, obtain the ecliptic longitude of each planet (in degrees) and determine its position in the corresponding signs (for example, 15° Taurus).
   • Calculations are performed for two individuals (synastry).

3. Calculation of aspects:

   • Compare the longitudes of the planets with each other, calculate the difference in degrees, and if this difference falls within the defined aspect range, output the corresponding information.

4. Diagram generation (graphics):

   • Using libraries for diagram construction (D3.js, Chart.js, Canvas in JavaScript, Matplotlib in Python, etc.), build an astrological circle divided into 12 sectors (360° / 12).
   • Place each planet in the corresponding sector according to the obtained data, and also depict aspects as lines connecting the planets.

5. Data storage:

   • Store all calculated values as variables for further use.
   • Based on the prompt, generate the textual part of the report (connecting OpenAI API).

6. PDF generation:

   • Assemble the obtained data into the appropriate template and generate the final PDF document, which will be sent to the client via email.

Our website operates on a standard stack: WordPress, HTML/CSS, JavaScript, PHP. 

The platform for developing the generator – we suggest considering your recommendations for choosing technologies for the backend. I have provided all necessary data for a complete analysis, and you can immediately provide a full assessment of the stack. 

We need to obtain a working MVP version of the generator that will immediately start generating profit (since the traffic is already there). All functionality of the MVP is implemented at a fixed price. All further extensions and improvements will be processed by agreement.

We are considering collaboration only with an independent developer, not a team/company.  It is important that the candidate is interested in the project and the final product, has development experience (specifically a portfolio), and can provide detailed feedback with an assessment of the technical stack, approximate implementation time for the MVP, and examples of completed backend projects.

If you have carefully reviewed the terms of reference and are interested in collaboration – send your detailed proposals. I am waiting only for serious proposals from specialists who are truly interested in the project.