For websites that are selling stuff or dealing with currencies, -like displaying prices of products, presenting parities (business-economy sites), multilanguage web apps- having the up-to-date exchange rates is pretty important.

Open Source Exchange Rates API is a free-to-use service that makes these rates reachable -updated every hour- in a clean JSON format.

The service collects all the exchange rates from the Google Calculator API (one by one) and pushes them in JSON format to a public GitHub code repository where everyone can reach.

It integrates tightly with Money.js, which is a must-bookmark JavaScript library for currency conversion.

Also, the data can be reached historically again in a simple API call.

FlyJSONP is a JavaScript library for making cross-domain GET and POST requests to services that support JSONP, and get a JSON response.

The library is easy-to-use, there is nothing complicated, very lightweight (1.13kb gzipped) and doesn't require any other JS frameworks.

It passes the POST requests through Yahoo's YQL and provides a complete control over the callback parameter name for GET requests.

There is an online playground provided for giving the library a try.

Tempo is a JSON rendering engine with a light footprint (4kb) for easily designing data templates using pure HTML.

The engine enables us to separate HTML – JavaScript completely and also simplifies dealing with AJAX content.

It also has support for nested and conditional templates (boolean and value-based).

Normally, there is always a chance that data templates being visible before rendered by the browser. To prevent this, you can hide them via CSS and Tempo will smartly remove any inline rules after it is completely rendered.

Tempo doesn't depend on any other library and degrades gracefully if JavaScript is not enabled.

There is a simple Twitter-related demo that shows how powerful it can be.

Signature Pad is a jQuery plugin which transforms an HTML form into a canvas where users can draw their signatures.

It has 2 modes:

• TypeIt mode where the user’s signature is automatically generated as HTML text and styled with @font-face from the input field where the name is typed.
• DrawIt mode where the users can draw their signatures on the canvas element.

The signature submitted is stored as a JSON array which makes re-generating it possible.

And, the plugin doesn't need to be used as its name suggests, you can ask users to draw anything and store it easily.

JsChat is an open source chat script that is built with Ruby (Sinatra), uses a simple protocol based on JSON and comes as a server/client application.

It is similar to IRC but simpler and has very useful features like:

• IRC-like commands: /names, /name new_name (/nick works too), /clear, /lastlog
• auto-linking: pasting an image displays it inline, Youtube and Vimeo videos will appear as well
• last messages are displayed when logged in

Users can "login to" or create multiple chatrooms (and they will be saved when logged out).

And, optionally, users can authenticate with their Twitter profiles.

Using JavaScript, it is possible to load HTML, XML or JSON data with XMLHttpRequest.

However cross-domain JavaScript requests (reaching remote pages) are not possible due to browser security limitations except JSONP-formatted JSON data.

Simple PHP Proxy is a PHP script which aims to fill this gap by creating a layer between your JavaScript code and the remote domain to get data in HTML, XML or JSON formats.

Some features of Simple PHP Proxy:

• requested URLs can be white-listed & validated against a regex.
• optionally forward client cookies / SID to the remote server.
• optionally forward configurable User Agent to the remote server.
• requests can use either GET or POST request methods.
• remote data can be delivered as-is with all remote headers intact.
• remote data can be wrapped in a JSON/P structure that includes status codes & remote headers.
• if using JSON/P & remote data is valid JSON, it will be merged into the resulting data object.

There is also a demo which you can request any URL.

ColorSuckr is a free online service which can extract colors from an image & generate color schemes.

It can be used in 3 ways:

• by mentioning the URL of the image
• via a bookmarklet
• or a Firefox add-on

Once the color schemes are ready, they can be downloaded as Adobe Swatch (.ASE) files or more schemes can be listed from COLOURlovers for any selected color.

ColorSuckr also offers the results in RSS, JSON & XML formats which makes an integration with any application possible.

MooFlow is a highly customizable coverflow-like image gallery that is built with MooTools.

It is easily & automatically setup by mentioning the HTML element that grabs the images.

MooFlow has various features like:

• fullscreen support
• browsing with mouse wheel
• browsing with keyboard
• autoplay & loop
• automated JavaScript image reflections

The script is also flexible when loading the images. The data source can be JSON or HTML with selector-filter.

And, its interface can be totally skinned via CSS.

InfoVis is an open source JavaScript data visualization toolkit offering multiple ways to present data using the canvas tag.

It is feeded with data in JSON format & some of the ready to use visualizations are:

• treemaps
• radial layouts
• bar charths, pie charts & more…

Besides a static presentations, InfoVis supports interactive animations which can be fired by any event (like mouseovers, clicks).

It has various methods to add/remove/update nodes & manipulate every aspect of the outputs.

The toolkit doesn’t depend on a JavaScript framework, can be used with any of them & easily updated for adding new features to it.

MooGenda is an event calendar script, built with MooTools, that reads events from JSON requests.

The calendar supports drag’n drops of events & in every action a JSON request is sent for instant updates.

This MooTools calendar supports 3 different views:

• day view
• week view
• month view

With clicks, the calendar switches between views with a sliding animation & displays the details of that day/view/month.