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Embedding excel in a webpage

I have read from Microsoft here that I can embed an excel sheet in a webpage. I have also read where I can embed a visio instance. Does anyone know if I can create a website that uses an excel instance and visio instance that is unique to each user's experience and draws from their custom database.
For example: say I have a pre-formatted excel sheet with fixed columns and I ask for the user to import their report card, and they do so. The database stores their report card information and outputs it to the excel spreadsheet instance.
Is this a possibility or can I only embed one single excel workbook that will be linked to the master and can not be customized for each user's experience of my webpage/web app?
It would be really cool if I could do the same with Visio as well. I have tried to find an exact answer to this, but I can not get a clearly defined differentiation of whether or not I can get unique instances, or whether all must be viewing the same master document.

You may need some non-free office server product to be able to do that (edit excel docs online). That can be SharePoint, OneDrive for Business (which is basically just another name for SharePoint), or Office Online server (the underlying technology).
Given that you have that in place, the rest is pretty easy - you can create a document per user, and just display it in IFRAME (you can google "WopiFrame" on how to do that exactly).
On the server, in principle, you can bind your Excel sheets to Visio drawings. So that when you edit the sheet, corresponding Visio drawing view is updated. Keep in mind, that is probably possible within a single SharePoint site.
Means, from M$ side, probably the assumed approach could be, you embed Excel and Visio frames in a web page, then embed that page into a SharePoint site, then host that on SharePoint online, and then pay for that on regular basis :)
If you don't want SharePoint, you can still go with Office Online to enable Excel editing in IFRAME on your own site; but here you'll loose Visio rendering, as it's only available in SP. And you'll need to build you own API. AFAIK, viewing office docs is free, editing is not (requires end-user office licensing). In case you would like to go this path, you could start over here: https://wopi.readthedocs.io/

To Display Excel Spreadsheet with Charts on Websites

Is there anyway to display Excel Spreadsheet with charts (Live, does not need to be editable) on Websites?
Currently I have some Excel reports with charts. I am building a website to display these spreadsheet data. The spreadsheet doesn't need to be editable. But I want it to be displayed right away, instead of a link downloading it locally every time and open it.
Is there anyway easy way I can do this?
Some methods that I have researched but would not work in my case:
Google Doc
Saving as html output in excel (I want it to be automatically. All the spreadsheet generation/ HTML code creation would be in linux)
Sharepoint
Thanks!

I would suggest to utilize Excel Services for that purpose.
Prerequisite: Excel Services service application has to be configured
Prepare excel data
Assume the following excel file
that contains the following items in the workbook:
table (how to Create or delete an Excel table in a worksheet)
chart
Important:
Before uploading file into SharePoint library, go to File -> Browse View Options -> choose Items in the Workbook as demonstrated below. Then save file and upload it into SharePoint Documents library.
Once the excel file is uploaded into Documents library the chart could be rendered in browser using the following endpoint:
Url: https://contoso.sharepoint.com/_vti_bin/ExcelRest.aspx/Documents/sample.xlsx/Model/Charts('Chart1')
Method: GET
Results
Display chart on page via ScriptEditor/ContentEditor web part
Content: <img src="/_vti_bin/ExcelRest.aspx/Documents/sample.xlsx/Model/Charts(%27Chart1%27)" alt=""/>
References
Using the Excel Services 2010 REST API

Let user load some content on a web page on Dropbox with the click of a `Save to Dropbox` button

I'd like to enhance some web pages of my site by giving the user the ability to automatically load some content (for example an image) on his/her Dropbox by just the click of a Save to Dropbox button.
Just with the simple logic available from Facebook, gPlus, Pinterest.
Is it possibile?
I explored the documentation but couldn't find and indication.

To let the user save in his/her Dropbox some files hostes on your web site you need the Saver
As the documentation states it is required to create a Dropbox app and obtain a data-app-key.
The web page has to load the Dropbox dropins JavaScript API.
Finally adding a "Save to Dropbox" button Saver button just requires inserting a link:
The Saver can also be triggered via JavaScript API allowing, for example, to design a custom button.
Detailed reference is here https://www.dropbox.com/developers/saver

How to convert a single page webapp into an offline format

I created a single page application using AngularJS. Is there a way to automatically convert it to an offline format like pdf or chm? The website contains multimedia content such as webms and ideally those should be preserved. Although having a single file (like a chm), would be preferable it would be sufficient to be able to view the contents of the website locally without having to use a web server.
Solutions like saving webpage as MHTML, HTML Help Workshop and WEB to CHM don't generate useful output. Allowing users to download the website and open the files directly doesn't work because of this error.

Export my SharePoint aspx page to a PDF file

I am working on an enterprise wiki site collection , and using the SharePoint designer I have manually added a link named “Print to PDF” as follow:-
But I am trying to implement the link functionalities, so when the user clink on the link, the page content (mainly any html components that are inside the rich text ) should be displayed inside a pdf file?
Can anyone advice how I can achieve this ,, can I write a javaScript code which can do the work ? Thanks

You can develop an ASPX page (actually preferably an ASHX handler) that does the work for you by accepting an URL to convert, which you then pass into a third party HTML to PDF library. The generated PDF file can then be returned to the user's browser.
Alternatively, have a look at this blog post (that I wrote, so big fat disclaimer about me being biased) that shows how you can buy a product off the shelf that does all the work for you.
You can read more about it here.
BTW, for questions related to SharePoint you may want to consider using sharepoint.stackexchange.com.