Glossary
API
API (Application Programming Interface)
An API is essentially a contract between two software programs that defines how they can talk to each other. When your website connects to Stripe for payment processing, Google Maps for location features, or Mailchimp for email marketing — it's using APIs.
Why APIs Matter for Website Costs
APIs significantly affect website development budgets:
| API Type | Typical Cost | Notes |
|---|---|---|
| Payment processing (Stripe, PayPal) | 2.9% + $0.30/transaction | No monthly fee, per-transaction |
| Maps (Google Maps) | $7/1,000 requests | Free tier: 200,000 requests/month |
| Email marketing (Mailchimp) | $0-$350/month | Depends on list size |
| SMS (Twilio) | $0.0079/message | Per message |
| AI/Chat (OpenAI) | $0.15-$40/1M tokens | Usage-based |
API vs No-API (Plugin) Approach
| Approach | Example | Pro | Con |
|---|---|---|---|
| Direct API integration | Custom Stripe checkout | Full control, no vendor lock-in | Requires developer |
| Plugin/extension | WooCommerce Stripe plugin | Quick, no code needed | Less control, plugin fees |
| SaaS widget | Embedded Calendly | Zero development | Branding limitations |
Common APIs in Website Development
- Payment: Stripe, PayPal, Square
- Authentication: Auth0, Firebase Auth, Clerk
- Maps/Location: Google Maps, Mapbox
- Email: SendGrid, Mailgun, Amazon SES
- Social Login: Google OAuth, Facebook Login
- Analytics: Google Analytics, Plausible, Mixpanel
- AI/Chat: OpenAI, Anthropic Claude, Gemini
Cost Implications When Planning Your Website
API costs are a hidden expense many clients underestimate. A website with payment processing, user authentication, email, and SMS can accumulate $200-$800/month in API fees before any custom development costs — especially as traffic grows.
See our web hosting cost guide for infrastructure costs and how much does a website cost for a complete budget breakdown. Use our website cost calculator to estimate your total project cost.