The allowance and processes to give programs access to connect and essentially, communicate with other programs. Their APIs are their languages.
It's a software-to-software interface that allow for separate parties to talk to each other without any previous user knowledge or intervention. It runs the processes behind the scenes. For example: Many online stores use these to allow you to enter your credit card information, and then the store uses the API to send the information to a remote application that will verify whether or not the information is correct.
API and the adjoining services are invisible to site users and software users. Their jobs run in the background providing a way for applications to work simultaneously.
There are several different programming languages, protocols and standards that make these services work.
SOAP (Simple Object Access Protocol)
This is what is responsibile for encoding XML messages so that they are received and understood by an operating system over any type of network protocol.
REST (Representational State Transfer)
An architechtural style of a coordinated constraints applied to components, connectors, and data elements. It ignores the details of component implementation and protocol syntax so that it may focus on the roles of components, their interaction and constraints with other components, and their interpretation of data elements.
This is considered as an alternative to SOAP.
Some of the API we suggest you to include in your application are:
Authentication / Authorization
Stormpath
Stormpath makes the entire user portion of your project dead simple: store users (and user data) securely, handle user permissions, handle all the email verification / password reset stuff instantly.
Analytics
Keen.io
Great API for building out custom analytics.
CDN
CloudFlare
CDN + DDoS protection! It’s what we use here at Stormpath.
Fastly
My favorite CDN. Amazing API. Very fast. Super customizable. Makes your website fast — really fast.
CRM
Intercom
A great customer CRM. Really easy, handles all sorts of customer communication channels — so amazing.
Dashboards
Ducksboard
I love these guys. Beautiful design. Straightforward API. Makes visualizing your project data simple.
Leftronic
Nice dashboard, great design. Great API. Better for geolocation stuff, in my opinion.
Databases
Bonsai
A great ElasticSearch provider.
Heroku Postgres
The best PostgreSQL hosting service ever created. Period.
MongoHQ
Our favorite MongoDB database provider.
Open Redis
Our favorite Redis provider. I’ve been using them forever — they’ve never gone down, or lost any data. Furthermore, they make scaling your stuff incredibly easy.
Deployment / Hosting
Heroku
My absolute favorite hosting company.
Flynn
up-and-coming Heroku competitor (built on top of Docker). It looks very promising if Heroku isn’t your thing.
Sendgrid
Send email via their API — easily.
Logging
Loggly
Easy log management
Monitoring / Debugging
New Relic
If you don’t have New Relic in your app — New Relic is 100% critical to building any modern application. It gives you the absolute best performance / monitoring information humanly possible.
RunScope
Debug API services. Monitor API services. Really valuable tool.
Payments
Stripe
Best damn credit card processor out there.
Coinbase
Best Bitcoin provider.
Firebase
Powerful API to store and sync data in realtime.
Pusher
Great API that makes web sockets easy.
Storage
Amazon S3
Can’t beat Amazon S3 for file storage / streaming. It’s the best.
Telephony
OpenCNAM
Caller ID, instantly.
Twilio
Make phone calls and SMS messages easily.
Testing
Travis CI
Unit and integration testing service. Free for open source stuff, paid for proprietary stuff