Optivest Price Calculator SPA
WordPress React single page app with secured API data feeding a price calculator inside the existing site.
Based in Cape Town, South Africa
Single page app developer in Cape Town for
React and Next.js business tools.
I build focused React and Next.js single page apps for Cape Town businesses. Browser-only when that is enough. API-connected when the workflow needs live data. Embedded inside WordPress, WooCommerce, Shopify, or a CRM when the business already has a system. Direct access to the developer who writes the code.
2017
Shipping single page apps since
9+
Years building SPAs
8
Free public tools live at /tools
CPT
Cape Town based, direct contact
Three Shapes
Three kinds of single page apps I build
Browser-only SPAs
Calculators, estimators, document generators, pricing tools, public lead-magnet apps. IndexedDB or localStorage for state. JSON export for backup. PDF or print for output. No backend. Your tool data stays in the browser. Right when the workflow is private, the inputs are short, and the output is a document or a number.
API-connected SPAs
React or Next.js front ends that read and write through external APIs. REST, GraphQL, WordPress REST, WooCommerce Store API, Shopify Storefront, CRM and ERP APIs, custom Node or PHP APIs. Right when the workflow needs live data, shared state, or write-back to a system of record.
Platform-embedded SPAs
Shortcode apps inside WordPress. Product selectors inside WooCommerce. Configurators inside Shopify. CRM admin screens. Internal dashboards. The SPA renders inside the platform the business already runs on, and writes through the platform APIs. Right when there is already a platform and the missing piece is one focused screen.
Cape Town, direct access
Based in Cape Town. Email, phone, or WhatsApp. Coffee if you are in town. No agency middle layer, no offshore handoff, no account-manager filter between you and the person writing the code.
When to Call
When a Cape Town business should call me about an SPA
The spreadsheet is doing a job that is too important to change
When the file has grown so load-bearing that everyone is afraid to touch it, the next version is usually a focused SPA. Browser-only if the data is private; API-connected if more than one person needs the same view.
The off-the-shelf tool does 80 percent and the last 20 percent matters
Most SaaS tools cover the average. The last 20 percent of the workflow is usually the part that earns money or saves time. A focused SPA fills the gap without forcing a platform migration.
The plugin marketplace cannot do the calculator, selector, or dashboard
WordPress and WooCommerce plugins cover the obvious cases. When the business needs a specific decision flow, pricing model, or admin screen, that is a SPA inside the existing CMS.
WordPress & WooCommerce›A previous contractor disappeared with the source
Rescue and rebuild work is part of the catalogue. A focused SPA in a known stack is usually the right replacement for a half-built bespoke app that no one can maintain.
The business has WordPress, WooCommerce, or Shopify already
The next feature should be one focused screen, not a new platform. Embedded SPAs sit inside the host platform and write through its APIs.
Shopify Development›The team is paying SaaS rent for a five-minute browser tool
Replacing a monthly SaaS bill with a browser-only SPA pays for itself within months for many micro to large businesses.
See free public tools›Projects
Public tools you can open now
Next.js | IndexedDB | localStorageFree South African Billing App
Browser-only invoices, quotes, credit notes in ZAR with VAT. IndexedDB, JSON backup, PDF print.
Open the Billing App›
Next.js | IndexedDB | UIF computeFree South African Payslip Generator
BCEA Section 33 payslips, UIF calculation, JSON backup, PDF output. For micro businesses and informal-segment employers.
Open the Payslip Generator›Next.js | localStorage | scenario compute
Free Profit Margin Calculator
Margin, markup, pricing analyzer with VAT, landed cost, scenario compare. Browser-only.
Open the Calculator›
Next.js | PERT compute | A4 PDFFree Project Estimator
PERT, risk register, milestones, printable A4 estimates. Spreadsheet logic in a browser-only SPA.
Open the Project Estimator›
Next.js | @dnd-kit | custom compilerEmail Signature & Template Generator
Drag-and-drop visual editor with a custom block-tree-to-email-safe-HTML compiler. IndexedDB storage.
Open the Signature Designer›Next.js | computed comparison
Payment Gateway Fee Comparator
Compare South African payment gateway fees side by side. Computed in the browser from published inputs.
Open the Comparator›
Next.js | amortisation computeCompound Interest Calculator
Loan repayment, service fees, amortisation table, interactive graph. Stateless browser-only SPA.
Open the Calculator›Next.js | QR generation
PayPal.Me Link Generator
PayPal.Me link from handle, optional amount and currency. QR code, share by WhatsApp or email.
Open the Generator›Client SPAs
Client single page apps already shipped (API-connected and embedded)
Eight client SPAs in production across WordPress, WooCommerce, Shopify and custom APIs. Real systems, real data, real users.
Optivest MedXpert SPA
Medical aid plan selection inside WordPress. Embedded React SPA, REST API, multi-step decision flow.
Storewell Parking Booking Dashboard
WordPress admin React SPA with custom REST API. Booking dashboard, calendar, role-aware screens.
ICA Custom Course/Product Selector
Public and admin React SPAs inside WordPress with custom MySQL and REST API. Course and product selection journey.
Truly Essential Shopify Credit System
Embedded React SPA in Shopify pages with Node API and ERP integration. Credit logic, customer portal, write-back to ERP.
Proficient Auto VIN Lookup App
JavaScript single page app inside a WordPress plugin. External VIN API lookup for an auto-transport workflow.
School Lookup App
React search single page app inside WordPress, using the Google Custom Search JSON API as the data layer.
Find-a-Surgeon-in-Your-Area App
React search SPA with PHP APIs, SQL, geolocation and map APIs. Practical pattern for "find one near me" tools.
Public Proof
Eight free single page apps live at /tools
Eight browser-only single page apps shipped as public free tools for South African businesses. Billing app, payslip generator, profit margin calculator, project estimator, email signature builder, payment gateway fee comparator, compound interest calculator, PayPal.Me link generator. All free, all browser-only, all built as React single page apps. Use them, share them, and see the SPA shape in production before deciding what to build for your own workflow. See all eight at /tools.
Testimonials
What Clients Say
“Excellent effort and work on a tricky project. Clear communication.”
Andy Hogg
“Anton is very knowledgeable and great at explaining technicality in a straightforward way. He has a ton of experience.”
Ushi Patel
“Anton did a great job. He is good at communicating back and forth to make sure everything is done the way you need it. He has my recommendation.”
John Shields
Process
How It Works
1
Tell me about the tool
Email, phone, or WhatsApp. Two sentences are usually enough to know if the shape is browser-only, API-connected, or embedded.
2
Free scope call
Cape Town in person if useful, otherwise Google Meet. One-page scope and fixed quote in ZAR, no agency markup.
3
Build in two-week cycles
Live preview each cycle. Handover with source, deployment notes, and a runbook.
Timeline
Typical Engagements
Most SPA work for Cape Town businesses falls into three engagement shapes:
- Browser-only SPA: 2-6 weeks. Calculators, estimators, document generators, public lead-magnet tools, internal staff tools.
- API-connected SPA: 4-10 weeks. React or Next.js front end against an existing or new REST/GraphQL API.
- Platform-embedded SPA: 4-10 weeks. Shortcode app inside WordPress, configurator inside Shopify, admin dashboard inside a CRM.
Direct Access
Bigger than that?
Multi-user platforms with auth, billing, and admin do not live here. They live on /services/custom-platform-applications. Backend APIs and integrations live on /services/api-servers-microservices.
FAQ
Frequently Asked Questions
Can a single page app connect to an external API?
Yes. That is one of the three shapes. REST and GraphQL are most common. The SPA holds the UI; the API holds the data. The school lookup app and the VIN lookup app are both shipped examples.
Can a single page app write data to WordPress, Shopify, or a CRM?
Yes. The Optivest MedXpert and ICA selector both write through WordPress REST. The Shopify credit system writes through a Node API into the client ERP. The Storewell dashboard writes through a custom WordPress REST API.
When does an SPA need a backend?
When more than one person needs to see the same data, when the data has to survive a browser wipe, when the workflow integrates with another system, or when the inputs are too long for the browser to be the right place to keep them.
Can you build this in Next.js?
Yes. Browser-only tools are usually plain React or Next.js with the data layer in IndexedDB. API-connected SPAs use Next.js routes or a separate Node API. Both shapes are in the back catalogue.
Can an SPA be a public SEO lead magnet?
Yes. The eight free tools at /tools are exactly that. They rank on their own and pull leads through to the rest of the site.
Can it start browser-only and grow into a platform later?
Yes. The cheapest path is to start with the smallest useful version and add an API and accounts when there is a reason to. The Free Billing App is the public version of that decision.
Looking for a single page app developer in Cape Town?
Tell me about the tool in two sentences. I review every enquiry personally and I will say up front whether the shape is browser-only, API-connected, or embedded.