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What is Instant Preview?

https://www.instantpreview.dev allows you to upload one or many html files for instant, private, temporary preview of your website.
It's like Netlify or Vercel or Cloudflare Pages but without the hassle.
No accounts, no projects, just upload files and see them online.

Uploading files

How to upload files with drag & drop:
  • go to https://www.instantpreview.dev and drag one or more files from a file manager
  • you can drag a whole directory
  • or click Select files for upload button and use file picker to choose files for upload
  • you can drop zip files and we'll extract files inside it
Upload files with curl:
  • curl -F name-on-server.html=@local-file.html -F second.html=@second.html https://www.instantpreview.dev/upload
  • curl --upload-file local-file.html https://www.instantpreview.dev/name-on-server.html
  • upload directory:
    • zip -9 -r website.zip www
      this will create website.zip file with the content of www directory
    • curl --upload-file website.zip https://www.instantpreview.dev/upload
      this uploads website.zip. We'll extract the files inside zip files
If upload is successful, the server returns URL under which the files are hosted. For example: https://www.instantpreview.dev/p/7DxnWY/
The uploads are private in that they are hosted under randomly generated url that is impossible to guess.

Premium sites

For $10 per site (one time) you can get a premium site, with the following benefits:
  • hosted under a unique domain <your-domain>.instantpreview.dev
  • do not expire
  • size increased from 10 MB to 100 MB
To get a premium site:
  • check that your domain is available by going to https://yourdomain.instantpreview.dev
  • if available, PayPal $10 to kkowalczyk@gmail.com
  • e-mail kkowalczyk@gmail.com with subject instantpreview.dev purchase and tell me your desired domain name and upload password
  • risk free: 30 days money back guarantee
You can also self-host for e.g. $7/month on https://render.com (or any other service that can host executables)

The limits

Instant Preview is not a web hosting service. It's meant to allow you to quickly preview HTML file or a website.
The largest individual file can be 5 MB.
Total size of uploaded files is less than 10 MB.
We don't abort downloads if they are larger than allowed, we just won't upload large files and only upload up to 10 MB of files.
The upload expires in about 2 hrs.
We won't upload executable files and video files.

SPA (Single Page Application) mode

In SPA mode, if a file doesn't exist and there is index.html, we'll serve index.html.
This is for Single Page Applications where URL routing happens in the on the client side.
You can see the SPA status on /p/${site}/_dir page.
You can toggle SPA mode by visiting /p/${site}/_spa
You can set SPA mode during upload from cmd-line by uploading to https://www.instantpreview.dev/upload?spa

Misc features

You can use _dir (/p/${site}/_dir) to list files in your site.
We support clean urls i.e. foo.html file is also available under foo.
Behavior for missing files:
  • in SPA mode, we return index.html, if exists. If doesn't exist, we follow non-SPA logic
  • if there is 404.html file, we serve that
  • otherwise we'll list available files (same as
If a file doesn't exist and there is 404.html file, we serve that.

Contact me

If you have question, feature requests etc., here's how you can reach me.

But why?

I was just annoyed by how hard it is to preview a website in development with Netlify / Vercel / Cloudflare Pages (yes, I've used them all).
It's possible but there's unnecessary friction. When I'm in development mode I just need a quick, temporary preview.
I got inspired by transfer.sh. They removed all friction from sharing files.
I decided to remove all friction from previewing websites.

Self hosting

You can self host this code on any service that can run Go services e.g. Heroku, fly.io, Digital Ocean Apps. Here are instructions for hosting on $7/month plan on https://render.com:

The technology

It's a very small project (took me 4 days to make it). Here's the technology I used
  • Go for the backend
  • mostly plain html / javascript + a dash of alpine.js to render lists
  • deployed to http://render.com (smallest, cheapest $7 instance is more than enough)
Written on Sep 8 2021.
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