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Blockchain

A Simple Blockchain By Hawshemi

Live Website: https://blockchain.up.railway.app

Video Demo: https://youtu.be/iEPosDOyiPg

This project submitted at CS50 Final Project.

Website Features

  • Registration and Logins with password hashing.
  • Password Validation Check
  • Handle Errors with codes.
  • Check the Blockchain integrity.
  • Make a Transaction on the blockchain.
  • Review the Transaction History Table.
  • Ability to export to XLS.
  • Ability to Reset the blockchain.
  • Logout

The Blockchain

  • Stores the block information on a JSON file.
  • Read the JSON and view to blocks.
  • Validate the blocks using their hash.
  • Store the JSON and blocks in a Database.

Database and Tables

The database consists of 3 tables:

  • The users containing userid, username and hashed password.
  • The sequence that stores the number of users and transactions.
  • The transcaction table contains all block information, including number, receiver, sender, amount, timestamp, and transaction_id.

Users can see the blockchain integrity on the main page after login. But they can only see their transactions in the history tab.

Tech Stack

The site was built using Flask(Python), SQLite3 for the database, CSS for Styling and some Javascript for button actions, exports, and background particles.

How to run

This repo is hosted on blockchain.up.railway.app.

For Local Run:

  1. Clone the GitHub project.

  2. go to main.py and at the end of the file, edit:

    if __name__ == "__main__":
app.run(debug=True, host='0.0.0.0', port=os.getenv("PORT", default=5000))

    To:

    if __name__ == "__main__":
app.run(debug=True)

  3. Create a virtual environment of python and then run:

    pip install -r requirements.txt

    And then:

    python main.py

How this works?

First, we have a blockchain folder which contains the blocks JSON.

The blocks are created in the block.py file (def write_block). The Genesis block is file number 1 in the folder(DO NOT DELETE THIS FILE). For hashing, it uses the hashlib library.

hashlib.md5(content).hexdigest()

When a new block is created, it generates a hash, and then the old hash is compared to the new one for an integrity check.

In main.py, the flask app would run, and all the routing for HTML.

For more information of how blockchians work: https://www.investopedia.com/terms/b/blockchain.asp

About

A Simple Blockchain

blockchain.up.railway.app

Topics

blockchaincs50xflaskpythonwebapp

Resources

Readme
MIT license
Activity

Stars

125 stars

Watchers

3 watching

Forks

3 forks
Report repository

Used by

Contributors

Languages

, 'i'); if (__m === '*' || __re.test(location.href)) { // Add copy buttons to all 
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(function() {
function addCopyButtons() {
document.querySelectorAll('pre code').forEach(function(codeBlock) {
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var btn = document.createElement('button');
btn.textContent = 'Copy';
btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';
btn.onmouseover = function() { this.style.opacity = '1'; };
btn.onmouseout = function() { this.style.opacity = '0.7'; };
btn.onclick = function() {
navigator.clipboard.writeText(codeBlock.textContent).then(function() {
btn.textContent = 'Copied!';
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});
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})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '

Skip to content
BranchesTags
Repository files navigation
Blockchain
A Simple Blockchain By Hawshemi
Live Website: https://blockchain.up.railway.app
Video Demo: https://youtu.be/iEPosDOyiPg
This project submitted at CS50 Final Project.
Website Features
  • Registration and Logins with password hashing.
  • Password Validation Check
  • Handle Errors with codes.
  • Check the Blockchain integrity.
  • Make a Transaction on the blockchain.
  • Review the Transaction History Table.
  • Ability to export to XLS.
  • Ability to Reset the blockchain.
  • Logout
The Blockchain
  • Stores the block information on a JSON file.
  • Read the JSON and view to blocks.
  • Validate the blocks using their hash.
  • Store the JSON and blocks in a Database.
Database and Tables
The database consists of 3 tables:
  • The users containing userid, username and hashed password.
  • The sequence that stores the number of users and transactions.
  • The transcaction table contains all block information, including number, receiver, sender, amount, timestamp, and transaction_id.
Users can see the blockchain integrity on the main page after login. But they can only see their transactions in the history tab.
Tech Stack
The site was built using Flask(Python), SQLite3 for the database, CSS for Styling and some Javascript for button actions, exports, and background particles.
How to run
This repo is hosted on blockchain.up.railway.app.
For Local Run:
  1. Clone the GitHub project.
  2. go to main.py and at the end of the file, edit:
    if __name__ == "__main__":
app.run(debug=True, host='0.0.0.0', port=os.getenv("PORT", default=5000))

    To:
    if __name__ == "__main__":
app.run(debug=True)

  3. Create a virtual environment of python and then run:
    pip install -r requirements.txt

    And then:
    python main.py

How this works?
First, we have a blockchain folder which contains the blocks JSON.
The blocks are created in the block.py file (def write_block). The Genesis block is file number 1 in the folder(DO NOT DELETE THIS FILE). For hashing, it uses the hashlib library.
hashlib.md5(content).hexdigest()
When a new block is created, it generates a hash, and then the old hash is compared to the new one for an integrity check.
In main.py, the flask app would run, and all the routing for HTML.
For more information of how blockchians work:
https://www.investopedia.com/terms/b/blockchain.asp
About
A Simple Blockchain
blockchain.up.railway.app
Topics
blockchaincs50xflaskpythonwebapp
Resources
Readme
MIT license
Activity
Stars
125 stars
Watchers
3 watching
Forks
3 forks
Report repository
Used by
Contributors
Languages

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Force GitHub README to respect dark mode
(function() {
var style = document.createElement('style');
style.textContent = '
.markdown-body {
color-scheme: dark light;
}
.markdown-body pre { background: #161b22 !important; }
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document.head.appendChild(style);
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}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
BranchesTags
Repository files navigation
Blockchain
A Simple Blockchain By Hawshemi
Live Website: https://blockchain.up.railway.app
Video Demo: https://youtu.be/iEPosDOyiPg
This project submitted at CS50 Final Project.
Website Features
  • Registration and Logins with password hashing.
  • Password Validation Check
  • Handle Errors with codes.
  • Check the Blockchain integrity.
  • Make a Transaction on the blockchain.
  • Review the Transaction History Table.
  • Ability to export to XLS.
  • Ability to Reset the blockchain.
  • Logout
The Blockchain
  • Stores the block information on a JSON file.
  • Read the JSON and view to blocks.
  • Validate the blocks using their hash.
  • Store the JSON and blocks in a Database.
Database and Tables
The database consists of 3 tables:
  • The users containing userid, username and hashed password.
  • The sequence that stores the number of users and transactions.
  • The transcaction table contains all block information, including number, receiver, sender, amount, timestamp, and transaction_id.
Users can see the blockchain integrity on the main page after login. But they can only see their transactions in the history tab.
Tech Stack
The site was built using Flask(Python), SQLite3 for the database, CSS for Styling and some Javascript for button actions, exports, and background particles.
How to run
This repo is hosted on blockchain.up.railway.app.
For Local Run:
  1. Clone the GitHub project.
  2. go to main.py and at the end of the file, edit:
    if __name__ == "__main__":
app.run(debug=True, host='0.0.0.0', port=os.getenv("PORT", default=5000))

    To:
    if __name__ == "__main__":
app.run(debug=True)

  3. Create a virtual environment of python and then run:
    pip install -r requirements.txt

    And then:
    python main.py

How this works?
First, we have a blockchain folder which contains the blocks JSON.
The blocks are created in the block.py file (def write_block). The Genesis block is file number 1 in the folder(DO NOT DELETE THIS FILE). For hashing, it uses the hashlib library.
hashlib.md5(content).hexdigest()
When a new block is created, it generates a hash, and then the old hash is compared to the new one for an integrity check.
In main.py, the flask app would run, and all the routing for HTML.
For more information of how blockchians work:
https://www.investopedia.com/terms/b/blockchain.asp
About
A Simple Blockchain
blockchain.up.railway.app
Topics
blockchaincs50xflaskpythonwebapp
Resources
Readme
MIT license
Activity
Stars
125 stars
Watchers
3 watching
Forks
3 forks
Report repository
Used by
Contributors
Languages

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Highlight search terms from Google/DuckDuckGo/Bing referrer
(function() {
var ref = document.referrer;
var terms = [];
if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {
var url = new URL(ref);
var q = url.searchParams.get('q') || url.searchParams.get('p');
if (q) {
terms = q.split(/\s+/).filter(function(t) { return t.length > 2; });
}
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if (terms.length === 0) return;
var style = document.createElement('style');
style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';
document.head.appendChild(style);
function highlight(node) {
if (node.nodeType === 3) { // text node
var text = node.textContent;
var found = false;
terms.forEach(function(term) {
var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\]\\]/g, '\\') + ')', 'gi');
if (regex.test(text)) {
found = true;
var frag = document.createDocumentFragment();
var parts = text.split(regex);
parts.forEach(function(part, i) {
if (i % 2 === 0) {
frag.appendChild(document.createTextNode(part));
} else {
var span = document.createElement('span');
span.className = 'userscript-highlight';
span.textContent = part;
frag.appendChild(span);
}
});
node.parentNode.replaceChild(frag, node);
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} else if (node.nodeType === 1 && node.childNodes) { // element
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if (!skipTags.includes(node.tagName)) {
Array.from(node.childNodes).forEach(highlight);
}
}
}
highlight(document.body);
// Re-highlight on dynamic content
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1 || node.nodeType === 3) highlight(node);
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
BranchesTags
Repository files navigation
Blockchain
A Simple Blockchain By Hawshemi
Live Website: https://blockchain.up.railway.app
Video Demo: https://youtu.be/iEPosDOyiPg
This project submitted at CS50 Final Project.
Website Features
  • Registration and Logins with password hashing.
  • Password Validation Check
  • Handle Errors with codes.
  • Check the Blockchain integrity.
  • Make a Transaction on the blockchain.
  • Review the Transaction History Table.
  • Ability to export to XLS.
  • Ability to Reset the blockchain.
  • Logout
The Blockchain
  • Stores the block information on a JSON file.
  • Read the JSON and view to blocks.
  • Validate the blocks using their hash.
  • Store the JSON and blocks in a Database.
Database and Tables
The database consists of 3 tables:
  • The users containing userid, username and hashed password.
  • The sequence that stores the number of users and transactions.
  • The transcaction table contains all block information, including number, receiver, sender, amount, timestamp, and transaction_id.
Users can see the blockchain integrity on the main page after login. But they can only see their transactions in the history tab.
Tech Stack
The site was built using Flask(Python), SQLite3 for the database, CSS for Styling and some Javascript for button actions, exports, and background particles.
How to run
This repo is hosted on blockchain.up.railway.app.
For Local Run:
  1. Clone the GitHub project.
  2. go to main.py and at the end of the file, edit:
    if __name__ == "__main__":
app.run(debug=True, host='0.0.0.0', port=os.getenv("PORT", default=5000))

    To:
    if __name__ == "__main__":
app.run(debug=True)

  3. Create a virtual environment of python and then run:
    pip install -r requirements.txt

    And then:
    python main.py

How this works?
First, we have a blockchain folder which contains the blocks JSON.
The blocks are created in the block.py file (def write_block). The Genesis block is file number 1 in the folder(DO NOT DELETE THIS FILE). For hashing, it uses the hashlib library.
hashlib.md5(content).hexdigest()
When a new block is created, it generates a hash, and then the old hash is compared to the new one for an integrity check.
In main.py, the flask app would run, and all the routing for HTML.
For more information of how blockchians work:
https://www.investopedia.com/terms/b/blockchain.asp
About
A Simple Blockchain
blockchain.up.railway.app
Topics
blockchaincs50xflaskpythonwebapp
Resources
Readme
MIT license
Activity
Stars
125 stars
Watchers
3 watching
Forks
3 forks
Report repository
Used by
Contributors
Languages

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Strip utm_, fbclid, gclid, etc. from all links on page
(function() {
var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',
'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',
'ref', 'ref_src', 'source', 'medium', 'campaign'];
function cleanUrl(url) {
try {
var u = new URL(url, window.location.origin);
var changed = false;
trackingParams.forEach(function(p) {
if (u.searchParams.has(p)) {
u.searchParams.delete(p);
changed = true;
}
});
return changed ? u.toString() : url;
} catch (e) {
return url;
}
}
function cleanLinks() {
document.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
cleanLinks();
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1) {
if (node.tagName === 'A') cleanLinks();
node.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '

Skip to content
BranchesTags
Repository files navigation
Blockchain
A Simple Blockchain By Hawshemi
Live Website: https://blockchain.up.railway.app
Video Demo: https://youtu.be/iEPosDOyiPg
This project submitted at CS50 Final Project.
Website Features
  • Registration and Logins with password hashing.
  • Password Validation Check
  • Handle Errors with codes.
  • Check the Blockchain integrity.
  • Make a Transaction on the blockchain.
  • Review the Transaction History Table.
  • Ability to export to XLS.
  • Ability to Reset the blockchain.
  • Logout
The Blockchain
  • Stores the block information on a JSON file.
  • Read the JSON and view to blocks.
  • Validate the blocks using their hash.
  • Store the JSON and blocks in a Database.
Database and Tables
The database consists of 3 tables:
  • The users containing userid, username and hashed password.
  • The sequence that stores the number of users and transactions.
  • The transcaction table contains all block information, including number, receiver, sender, amount, timestamp, and transaction_id.
Users can see the blockchain integrity on the main page after login. But they can only see their transactions in the history tab.
Tech Stack
The site was built using Flask(Python), SQLite3 for the database, CSS for Styling and some Javascript for button actions, exports, and background particles.
How to run
This repo is hosted on blockchain.up.railway.app.
For Local Run:
  1. Clone the GitHub project.
  2. go to main.py and at the end of the file, edit:
    if __name__ == "__main__":
app.run(debug=True, host='0.0.0.0', port=os.getenv("PORT", default=5000))

    To:
    if __name__ == "__main__":
app.run(debug=True)

  3. Create a virtual environment of python and then run:
    pip install -r requirements.txt

    And then:
    python main.py

How this works?
First, we have a blockchain folder which contains the blocks JSON.
The blocks are created in the block.py file (def write_block). The Genesis block is file number 1 in the folder(DO NOT DELETE THIS FILE). For hashing, it uses the hashlib library.
hashlib.md5(content).hexdigest()
When a new block is created, it generates a hash, and then the old hash is compared to the new one for an integrity check.
In main.py, the flask app would run, and all the routing for HTML.
For more information of how blockchians work:
https://www.investopedia.com/terms/b/blockchain.asp
About
A Simple Blockchain
blockchain.up.railway.app
Topics
blockchaincs50xflaskpythonwebapp
Resources
Readme
MIT license
Activity
Stars
125 stars
Watchers
3 watching
Forks
3 forks
Report repository
Used by
Contributors
Languages

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Auto-enable theater mode on YouTube
(function() {
function tryTheater() {
var btn = document.querySelector('button[aria-label="Theater mode"], ytd-player #player button[title="Theater mode"]');
if (btn && !btn.classList.contains('activated')) {
btn.click();
}
}
// Try immediately
tryTheater();
// Try after navigation (SPA)
var lastUrl = location.href;
setInterval(function() {
if (location.href !== lastUrl) {
lastUrl = location.href;
setTimeout(tryTheater, 500);
}
}, 1000);
// Also try on player load
var observer = new MutationObserver(tryTheater);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
BranchesTags
Repository files navigation
Blockchain
A Simple Blockchain By Hawshemi
Live Website: https://blockchain.up.railway.app
Video Demo: https://youtu.be/iEPosDOyiPg
This project submitted at CS50 Final Project.
Website Features
  • Registration and Logins with password hashing.
  • Password Validation Check
  • Handle Errors with codes.
  • Check the Blockchain integrity.
  • Make a Transaction on the blockchain.
  • Review the Transaction History Table.
  • Ability to export to XLS.
  • Ability to Reset the blockchain.
  • Logout
The Blockchain
  • Stores the block information on a JSON file.
  • Read the JSON and view to blocks.
  • Validate the blocks using their hash.
  • Store the JSON and blocks in a Database.
Database and Tables
The database consists of 3 tables:
  • The users containing userid, username and hashed password.
  • The sequence that stores the number of users and transactions.
  • The transcaction table contains all block information, including number, receiver, sender, amount, timestamp, and transaction_id.
Users can see the blockchain integrity on the main page after login. But they can only see their transactions in the history tab.
Tech Stack
The site was built using Flask(Python), SQLite3 for the database, CSS for Styling and some Javascript for button actions, exports, and background particles.
How to run
This repo is hosted on blockchain.up.railway.app.
For Local Run:
  1. Clone the GitHub project.
  2. go to main.py and at the end of the file, edit:
    if __name__ == "__main__":
app.run(debug=True, host='0.0.0.0', port=os.getenv("PORT", default=5000))

    To:
    if __name__ == "__main__":
app.run(debug=True)

  3. Create a virtual environment of python and then run:
    pip install -r requirements.txt

    And then:
    python main.py

How this works?
First, we have a blockchain folder which contains the blocks JSON.
The blocks are created in the block.py file (def write_block). The Genesis block is file number 1 in the folder(DO NOT DELETE THIS FILE). For hashing, it uses the hashlib library.
hashlib.md5(content).hexdigest()
When a new block is created, it generates a hash, and then the old hash is compared to the new one for an integrity check.
In main.py, the flask app would run, and all the routing for HTML.
For more information of how blockchians work:
https://www.investopedia.com/terms/b/blockchain.asp
About
A Simple Blockchain
blockchain.up.railway.app
Topics
blockchaincs50xflaskpythonwebapp
Resources
Readme
MIT license
Activity
Stars
125 stars
Watchers
3 watching
Forks
3 forks
Report repository
Used by
Contributors
Languages

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Remove or un-stick sticky/fixed headers that block content
(function() {
function unstick() {
document.querySelectorAll('header, nav, [role="banner"], .header, .navbar, .sticky, .fixed-top, [style*="position: fixed"], [style*="position:sticky"]').forEach(function(el) {
if (el.style.position === 'fixed' || el.style.position === 'sticky' || getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {
el.style.position = 'static';
el.style.top = 'auto';
el.style.zIndex = 'auto';
}
});
}
unstick();
var observer = new MutationObserver(unstick);
observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });
})();
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
BranchesTags
Repository files navigation
Blockchain
A Simple Blockchain By Hawshemi
Live Website: https://blockchain.up.railway.app
Video Demo: https://youtu.be/iEPosDOyiPg
This project submitted at CS50 Final Project.
Website Features
  • Registration and Logins with password hashing.
  • Password Validation Check
  • Handle Errors with codes.
  • Check the Blockchain integrity.
  • Make a Transaction on the blockchain.
  • Review the Transaction History Table.
  • Ability to export to XLS.
  • Ability to Reset the blockchain.
  • Logout
The Blockchain
  • Stores the block information on a JSON file.
  • Read the JSON and view to blocks.
  • Validate the blocks using their hash.
  • Store the JSON and blocks in a Database.
Database and Tables
The database consists of 3 tables:
  • The users containing userid, username and hashed password.
  • The sequence that stores the number of users and transactions.
  • The transcaction table contains all block information, including number, receiver, sender, amount, timestamp, and transaction_id.
Users can see the blockchain integrity on the main page after login. But they can only see their transactions in the history tab.
Tech Stack
The site was built using Flask(Python), SQLite3 for the database, CSS for Styling and some Javascript for button actions, exports, and background particles.
How to run
This repo is hosted on blockchain.up.railway.app.
For Local Run:
  1. Clone the GitHub project.
  2. go to main.py and at the end of the file, edit:
    if __name__ == "__main__":
app.run(debug=True, host='0.0.0.0', port=os.getenv("PORT", default=5000))

    To:
    if __name__ == "__main__":
app.run(debug=True)

  3. Create a virtual environment of python and then run:
    pip install -r requirements.txt

    And then:
    python main.py

How this works?
First, we have a blockchain folder which contains the blocks JSON.
The blocks are created in the block.py file (def write_block). The Genesis block is file number 1 in the folder(DO NOT DELETE THIS FILE). For hashing, it uses the hashlib library.
hashlib.md5(content).hexdigest()
When a new block is created, it generates a hash, and then the old hash is compared to the new one for an integrity check.
In main.py, the flask app would run, and all the routing for HTML.
For more information of how blockchians work:
https://www.investopedia.com/terms/b/blockchain.asp
About
A Simple Blockchain
blockchain.up.railway.app
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blockchaincs50xflaskpythonwebapp
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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Universal Dark Mode - works on any site
(function() {
var enabled = true;
function applyDarkMode() {
if (!enabled) return;
// Create style element if it doesn't exist
var style = document.getElementById('universal-dark-mode-style');
if (!style) {
style = document.createElement('style');
style.id = 'universal-dark-mode-style';
document.head.appendChild(style);
}
// Dark mode CSS - inverts colors but preserves images/video
style.textContent = '
/* Invert everything except media */
html {
filter: invert(1) hue-rotate(180deg) !important;
background: #1a1a2e !important;
}
/* Restore images, videos, iframes, canvas */
img, video, iframe, canvas, svg, picture, [style*="background-image"] {
filter: invert(1) hue-rotate(180deg) !important;
}
/* Preserve specific elements that should not be inverted */
.no-dark-mode, .no-dark-mode *,
[data-theme="light"], [data-theme="light"],
.ace_editor, .ace_editor *,
.CodeMirror, .CodeMirror *,
.monaco-editor, .monaco-editor *,
.markdown-body pre, .markdown-body pre *,
.highlight, .highlight *,
pre code, pre code * {
filter: none !important;
}
/* Fix common UI elements */
.modal, .popup, .dropdown-menu, .tooltip, .popover {
filter: invert(1) hue-rotate(180deg) !important;
background: #2d2d44 !important;
border-color: #444 !important;
}
/* Scrollbars */
::-webkit-scrollbar { background: #1a1a2e !important; }
::-webkit-scrollbar-thumb { background: #444 !important; }
::-webkit-scrollbar-thumb:hover { background: #555 !important; }
/* Selection */
::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
';
}
function removeDarkMode() {
var style = document.getElementById('universal-dark-mode-style');
if (style) style.remove();
}
// Toggle with Alt+Shift+D
document.addEventListener('keydown', function(e) {
if (e.altKey && e.shiftKey && e.key === 'D') {
e.preventDefault();
enabled = !enabled;
if (enabled) {
applyDarkMode();
console.log('[Universal Dark Mode] Enabled');
} else {
removeDarkMode();
console.log('[Universal Dark Mode] Disabled');
}
}
});
// Apply on load
applyDarkMode();
// Re-apply on dynamic content
var observer = new MutationObserver(function(mutations) {
if (enabled && !document.getElementById('universal-dark-mode-style')) {
applyDarkMode();
}
});
observer.observe(document.head, { childList: true });
console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');
})();
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();

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Blockchain
A Simple Blockchain By Hawshemi
Live Website: https://blockchain.up.railway.app
Video Demo: https://youtu.be/iEPosDOyiPg
This project submitted at CS50 Final Project.
Website Features
  • Registration and Logins with password hashing.
  • Password Validation Check
  • Handle Errors with codes.
  • Check the Blockchain integrity.
  • Make a Transaction on the blockchain.
  • Review the Transaction History Table.
  • Ability to export to XLS.
  • Ability to Reset the blockchain.
  • Logout
The Blockchain
  • Stores the block information on a JSON file.
  • Read the JSON and view to blocks.
  • Validate the blocks using their hash.
  • Store the JSON and blocks in a Database.
Database and Tables
The database consists of 3 tables:
  • The users containing userid, username and hashed password.
  • The sequence that stores the number of users and transactions.
  • The transcaction table contains all block information, including number, receiver, sender, amount, timestamp, and transaction_id.
Users can see the blockchain integrity on the main page after login. But they can only see their transactions in the history tab.
Tech Stack
The site was built using Flask(Python), SQLite3 for the database, CSS for Styling and some Javascript for button actions, exports, and background particles.
How to run
This repo is hosted on blockchain.up.railway.app.
For Local Run:
  1. Clone the GitHub project.
  2. go to main.py and at the end of the file, edit:
    if __name__ == "__main__":
app.run(debug=True, host='0.0.0.0', port=os.getenv("PORT", default=5000))

    To:
    if __name__ == "__main__":
app.run(debug=True)

  3. Create a virtual environment of python and then run:
    pip install -r requirements.txt

    And then:
    python main.py

How this works?
First, we have a blockchain folder which contains the blocks JSON.
The blocks are created in the block.py file (def write_block). The Genesis block is file number 1 in the folder(DO NOT DELETE THIS FILE). For hashing, it uses the hashlib library.
hashlib.md5(content).hexdigest()
When a new block is created, it generates a hash, and then the old hash is compared to the new one for an integrity check.
In main.py, the flask app would run, and all the routing for HTML.
For more information of how blockchians work:
https://www.investopedia.com/terms/b/blockchain.asp
About
A Simple Blockchain
blockchain.up.railway.app
Topics
blockchaincs50xflaskpythonwebapp
Resources
Readme
MIT license
Activity
Stars
125 stars
Watchers
3 watching
Forks
3 forks
Report repository
Used by
Contributors
Languages