X’s Pay-Per-Use pricing changed how I think about API integrations. Before it existed, “display a Twitter/X timeline on a website” meant either a bloated embed widget or a $200/month API plan — neither made sense for small projects.

Pay-Per-Use flips that. You pay per request. For fetching 10 posts three times a day, the real-world cost lands around $2–3/month. That’s a different conversation.

This article covers how I implemented X API v2 timeline fetching in PHP/WordPress — including the cost math, the API structure, retweet handling, caching strategy, and two WP-Cron gotchas that will bite you if you’re not ready.

Cost Breakdown First

Before writing a line of code, it’s worth understanding what you’re paying for.

Timeline fetching is a two-step process:

At 10 posts × 3 updates/day, the ceiling is $0.060 × 90 = $5.40/month. In practice it’s lower.

The no-duplicate-billing rule

X API does not charge twice for the same post within a 24-hour UTC window. On the second and third daily updates, you only pay for newly published posts. For accounts that don’t post constantly, the second and third updates often cost almost nothing. Real-world cost for most use cases: $2–3/month.

One important caveat: X has stated that Pay-Per-Use is a pilot program with provisional pricing that may change. Always verify current rates at developer.x.com before building anything that depends on these numbers.

Authentication

Bearer Token only. App-only OAuth 2.0. No user context needed for public timelines.

$response = wp_remote_get( $url, [
    'headers' => [
        'Authorization' => 'Bearer ' . $bearer_token,
    ],
    'timeout' => 15,
] );

If you’re in WordPress, use wp_remote_get() instead of curl or file_get_contents. It respects WordPress SSL settings and timeout configuration out of the box.

Step 1: User Lookup

GET https://api.twitter.com/2/users/by/username/{username}

You need the numeric user ID to call the timeline endpoint. This call costs $0.010.

$url      = 'https://api.twitter.com/2/users/by/username/' . rawurlencode( $username );
$response = wp_remote_get( $url, [ 'headers' => $headers ] );
$data     = json_decode( wp_remote_retrieve_body( $response ), true );
$user_id  = $data['data']['id'];

Note: use rawurlencode() on the username, not urlencode(). The latter encodes spaces as +, which breaks the endpoint.

Step 2: Timeline Fetch

GET https://api.twitter.com/2/users/{id}/tweets

The expansions and field parameters are where most of the complexity lives.

$params = http_build_query( [
    'max_results'  => 10,
    'tweet.fields' => 'created_at,entities,attachments,referenced_tweets',
    'expansions'   => 'attachments.media_keys,referenced_tweets.id,referenced_tweets.id.author_id',
    'media.fields' => 'url,preview_image_url,type,variants,width,height',
    'user.fields'  => 'name,profile_image_url,username',
    'exclude'      => 'replies', // optional: hide replies
] );

$url = 'https://api.twitter.com/2/users/' . $user_id . '/tweets?' . $params;

Important: max_results has a minimum of 5. Requesting fewer than 5 returns an API error. Plan your display logic accordingly.

Retweet Handling (The Tricky Part)

When a retweet appears in the timeline, the API returns a reference to the original post — not the content itself. This trips a lot of people up.

The fix: include referenced_tweets.id in your expansions. The original post data will appear in includes.tweets in the response.

$tweets   = $data['data'];             // timeline posts
$includes = $data['includes'] ?? [];   // expanded data

foreach ( $tweets as $tweet ) {
    $ref_tweets = $tweet['referenced_tweets'] ?? [];

    foreach ( $ref_tweets as $ref ) {
        if ( $ref['type'] === 'retweeted' ) {
            // find the original in includes.tweets
            $original = array_filter(
                $includes['tweets'] ?? [],
                fn( $t ) => $t['id'] === $ref['id']
            );
            $original = array_values( $original )[0] ?? null;
        }

        if ( $ref['type'] === 'quoted' ) {
            // same lookup, different type
        }
    }
}

Type values to know:

• retweeted — standard retweet
• quoted — quote tweet
• replied_to — reply (usually excluded via the exclude param)

Media attached to referenced tweets is also in includes.media, keyed by media_key. You’ll need to cross-reference tweet.attachments.media_keys against includes.media to render images and video.

Caching Strategy: Stale-While-Revalidate

Never call the API on every page load. It defeats the purpose of caching and burns through your credits.

The pattern I use: WordPress Transients + Stale-While-Revalidate (SWR).

function get_timeline_data() {
    $cached = get_transient( 'xtl_timeline_data' );

    if ( $cached !== false ) {
        $age = time() - $cached['last_updated'];

        if ( $age > 12 * HOUR_IN_SECONDS ) {
            // Stale but present: serve it, refresh in background
            wp_schedule_single_event( time(), 'xtl_swr_update_event' );
        }

        return $cached;
    }

    // No cache: schedule a fetch, return nothing for now
    wp_schedule_single_event( time(), 'xtl_swr_update_event' );
    return false;
}

The tradeoff: first-time visitors see nothing until the background fetch completes (usually a few seconds). Every subsequent visitor gets instant cached content. For most use cases this is acceptable.

Store your fetched data with a TTL long enough that it won’t expire between scheduled updates:

set_transient( 'xtl_timeline_data', $data, DAY_IN_SECONDS );

Two WP-Cron Gotchas

1. DST drift with wp_schedule_event('daily')

WordPress’s daily interval is a fixed 86400 seconds. During daylight saving time transitions, this causes scheduled events to drift by an hour. If you need updates at specific times, use wp_schedule_single_event() and re-schedule after each run:

// After executing, schedule the next occurrence
$next = strtotime( 'tomorrow ' . $time_str, current_time( 'timestamp' ) );
wp_schedule_single_event(
    $next,
    'xtl_cron_update_event',
    [ [ 'time_str' => $time_str ] ]
);

This keeps the scheduled time accurate regardless of DST changes.

2. wp_clear_scheduled_hook() doesn’t remove argument-keyed events

If you’re scheduling cron events with arguments (as above), wp_clear_scheduled_hook() will silently fail to remove them. Old events accumulate every time you save settings.

The fix: iterate _get_cron_array() and unschedule explicitly.

function clear_cron_events() {
    $crons = _get_cron_array();

    foreach ( (array) $crons as $timestamp => $cron ) {
        if ( ! isset( $cron['xtl_cron_update_event'] ) ) {
            continue;
        }
        foreach ( $cron['xtl_cron_update_event'] as $data ) {
            wp_unschedule_event(
                $timestamp,
                'xtl_cron_update_event',
                $data['args'] ?? []
            );
        }
    }
}

Call this before registering new cron events whenever settings change.

Rate Limit Handling

When you hit a 429, back off for at least an hour. A simple Transient-based cooldown works well:

if ( 429 === wp_remote_retrieve_response_code( $response ) ) {
    set_transient( 'xtl_api_cooldown', true, HOUR_IN_SECONDS );
    return new WP_Error( 'rate_limited', 'X API rate limit exceeded.' );
}

Check for the cooldown before every API call:

if ( get_transient( 'xtl_api_cooldown' ) ) {
    return; // skip until cooldown clears
}

Key Takeaways

On cost: The no-duplicate-billing rule makes Pay-Per-Use more affordable than the raw numbers suggest. Second and third daily updates often cost almost nothing for low-volume accounts.

On retweets: The most common implementation mistake. Always use expansions=referenced_tweets.id and look up the original in includes.tweets. Don’t assume the content is in data.

On caching: SWR is the right pattern for external API data in WordPress. Serve stale content immediately and refresh in the background — don’t make visitors wait.

On WP-Cron: Two silent failure modes that are easy to miss: DST drift with daily interval, and argument-keyed events not being removed by wp_clear_scheduled_hook().

I packaged this implementation into two WordPress plugins if you’d rather skip the plumbing:

• X Timeline — displays a configurable timeline feed with retweet support, filters, and auto-update scheduling
• X Pinned Post — fetches only the pinned post from an account, at a lower API cost per cycle

ikka.inc — design and web production studio based in Japan.

The Problem: Many Flutter developers overuse setState(), calling it even when variable changes don’t affect the UI. Every unnecessary setState() is a potential drop from 60 FPS to 59 FPS in complex interfaces.

Chapter 1: When setState Is Actually Unnecessary

Let’s examine a classic example found in 80% of applications: data entry forms. Developers often write:

class MyForm extends StatefulWidget {
  @override
  _MyFormState createState() => _MyFormState();
}

class _MyFormState extends State<MyForm> {
  String _username = '';
  String _password = '';

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        TextField(
          onChanged: (value) {
            setState(() {          // ❌ UNNECESSARY!
              _username = value;   // This variable is NOT used in UI
            });
          },
        ),
        TextField(
          onChanged: (value) {
            setState(() {          // ❌ UNNECESSARY!
              _password = value;   // This variable is also NOT in UI
            });
          },
        ),
        ElevatedButton(
          onPressed: () {
            // Send data to server
            _sendToServer(_username, _password);
          },
          child: Text('Submit'),
        ),
      ],
    );
  }

  void _sendToServer(String user, String pass) {
    // Send data...
  }
}

What’s wrong here? Every character typed triggers a complete widget rebuild, even though nothing visually changes! The user sees just the cursor blinking, but under the hood Flutter rebuilds the entire widget tree.
The right approach: If data is only needed for logic or server submission — store it without UI binding:

class _MyFormState extends State<MyForm> {
  // These variables are NOT used in build()
  final TextEditingController _usernameController = TextEditingController();
  final TextEditingController _passwordController = TextEditingController();

  @override
  void initState() {
    super.initState();
    // You can add listeners for additional logic
    _usernameController.addListener(() {
      print('Username changed: ${_usernameController.text}');
      // You can do validation, debounce, etc. here
    });
  }

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        TextField(controller: _usernameController),
        TextField(controller: _passwordController),
        ElevatedButton(
          onPressed: () {
            // Take data directly from controllers
            _sendToServer(
              _usernameController.text,
              _passwordController.text,
            );
          },
          child: Text('Submit'),
        ),
      ],
    );
  }
}

Key principle: If a variable isn’t displayed in build() and doesn’t affect how other widgets are displayed — it’s not part of UI state and doesn’t need setState().

Chapter 2: When setState IS Needed — Do It Precisely

There are cases where a variable truly affects UI, but that doesn’t mean you need to rebuild everything. Let’s look at smarter approaches.

❌ Typical case of excessive setState:

class ProductCard extends StatefulWidget {
  @override
  _ProductCardState createState() => _ProductCardState();
}

class _ProductCardState extends State<ProductCard> {
  bool _isFavorite = false;
  bool _isInCart = false;

  @override
  Widget build(BuildContext context) {
    return Card(
      child: Column(
        children: [
          Image.network('...'),
          Text('Product Name'),
          Row(
            children: [
              IconButton(
                icon: Icon(
                  _isFavorite ? Icons.favorite : Icons.favorite_border,
                  color: _isFavorite ? Colors.red : Colors.grey,
                ),
                onPressed: () {
                  setState(() {          // ❌ Rebuilds the ENTIRE Card!
                    _isFavorite = !_isFavorite;
                  });
                },
              ),
              IconButton(
                icon: Icon(
                  _isInCart ? Icons.shopping_cart : Icons.add_shopping_cart,
                  color: _isInCart ? Colors.green : Colors.grey,
                ),
                onPressed: () {
                  setState(() {          // ❌ Rebuilds the ENTIRE Card again!
                    _isInCart = !_isInCart;
                  });
                },
              ),
            ],
          ),
        ],
      ),
    );
  }
}

Problem: We’re changing only the button color and icon, but rebuilding the entire product card with image, text, and all other elements!

✅ Solution 1: ValueNotifier for precise updates

class ProductCard extends StatelessWidget {
  final ValueNotifier<bool> _isFavorite = ValueNotifier<bool>(false);
  final ValueNotifier<bool> _isInCart = ValueNotifier<bool>(false);

  @override
  Widget build(BuildContext context) {
    return Card(
      child: Column(
        children: [
          Image.network('...'),  // ❌ This part WON'T rebuild
          Text('Product Name'),   // ❌ This either
          Row(
            children: [
              // ✅ Only this icon will rebuild
              ValueListenableBuilder<bool>(
                valueListenable: _isFavorite,
                builder: (context, isFavorite, child) {
                  return IconButton(
                    icon: Icon(
                      isFavorite ? Icons.favorite : Icons.favorite_border,
                      color: isFavorite ? Colors.red : Colors.grey,
                    ),
                    onPressed: () {
                      _isFavorite.value = !isFavorite; // Just change value
                    },
                  );
                },
              ),
              // ✅ And this icon too
              ValueListenableBuilder<bool>(
                valueListenable: _isInCart,
                builder: (context, isInCart, child) {
                  return IconButton(
                    icon: Icon(
                      isInCart ? Icons.shopping_cart : Icons.add_shopping_cart,
                      color: isInCart ? Colors.green : Colors.grey,
                    ),
                    onPressed: () {
                      _isInCart.value = !isInCart;
                    },
                  );
                },
              ),
            ],
          ),
        ],
      ),
    );
  }
}

What changed:

• Product image and text no longer rebuild on click
• Only the specific icon updates
• Code became more declarative

✅ Solution 2: Extract changing part into separate StatefulWidget

class FavoriteButton extends StatefulWidget {
  @override
  _FavoriteButtonState createState() => _FavoriteButtonState();
}

class _FavoriteButtonState extends State<FavoriteButton> {
  bool _isFavorite = false;

  @override
  Widget build(BuildContext context) {
    return IconButton(
      icon: Icon(
        _isFavorite ? Icons.favorite : Icons.favorite_border,
        color: _isFavorite ? Colors.red : Colors.grey,
      ),
      onPressed: () {
        setState(() {
          _isFavorite = !_isFavorite; // Only button rebuilds
        });
      },
    );
  }
}

// Use in main widget
class ProductCard extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Card(
      child: Column(
        children: [
          Image.network('...'),
          Text('Product Name'),
          Row(
            children: [
              FavoriteButton(),      // Isolated state
              CartButton(),          // Another isolated state
            ],
          ),
        ],
      ),
    );
  }
}

Chapter 3: Checklist and Practical Rules

The 5-Second Rule
Before writing setState(), ask yourself:

“If I change this variable, will the user see visual changes within the next 5 seconds?”

If no (data goes to server, saves to DB, used for calculations) — you don’t need setState().

Simple Test for Your Code
Try temporarily commenting out setState():

onChanged: (value) {
  // setState(() {          // Commented out
    _someValue = value;    // Data still saves!
  // });
}

If UI works correctly — setState was unnecessary.

Strategy Guide:

1. Variable doesn’t affect UI → simple assignment

_apiToken = 'new_token';  // For sending requests
_userData = json;         // For processing
_cache = data;            // For storage

2 Affects one small element → ValueNotifier + ValueListenableBuilder
3 Affects several related widgets → extract to separate StatefulWidget
4 Affects entire screen/widget → setState() (use rarely and deliberately)

Typical Scenarios Without setState:

// Logging and analytics
onPressed: () {
  _clickCounter++;        // Just a variable
  _logEvent('button_click');
}

// Timers for logic
Timer.periodic(Duration(seconds: 30), (timer) {
  _lastUpdate = DateTime.now();  // For internal logic
  _checkForUpdates();
});

// Data caching
Future<void> _loadData() async {
  final data = await api.fetchData();
  _cachedData = data;     // Save, but don't rebuild
  _processData(data);
}

Conclusion: Ultimate Cheatsheet

When NOT to use setState:
• Data sent to server
• Saved to database/cache
• Used for logic/calculations
• For analytics/logging
• Temporary processing variables
When setState needed, but precisely:
• Button color/icon changes → ValueNotifier
• Text field updates → separate widget
• UI element state toggles → isolated state
When setState is justified:
• Large portion of screen changes
• Complex animation updates
• Entire list/table rebuilds

Remember: Flutter is not React. You don’t need to update state on every change. Separate UI state from business logic, and your app will run smoothly even on low-end devices.

Every unnecessary setState() is a step from “works fine” to “slideshow mode.” Be intentional about state management!

Disclosure: This post includes affiliate links; I may receive compensation if you purchase products or services from the different links provided in this article.

Hello Devs, in 2026, the AI era, System Design has become one of the most sought-after skills for software engineers, solution architects, and senior developers.

Whether you’re aiming for a FAANG-level interview, building the next unicorn startup, or designing scalable systems in AI, blockchain, or cloud computing, a deep understanding of system design is no longer optional — it’s essential.

Over the past few years, I’ve explored more than 30 books and courses from platforms like ByteByteGo, Educative.io, Udemy, Exponent, Codemia.io, Bugfree.ai, and Designgurus.io, plus a handful of top-rated books.

My goal was to find resources that don’t just explain concepts in theory but also show you how to apply them to real-world systems, with case studies, architectural diagrams, and hands-on practice.

After years of learning and testing, I’ve narrowed it down to my top 5 picks for mastering system design in 2026.

How I Chose These Courses and Platforms?

To ensure this list stays relevant and valuable, I evaluated each course based on these criteria:

• Content Quality & Depth — Does it cover core topics like scalability, distributed systems, load balancing, caching, databases, and microservices?
• Real-World Applications — Are there examples from actual systems like Netflix, Uber, WhatsApp, and ChatGPT?
• Practical Learning — Does it include case studies, exercises, and diagram walkthroughs? Does the platform provide features for practicing?
• Instructor Expertise — Are the instructors experienced engineers or architects with real-world experience?
• Community & Support — Is there a way to ask questions, get feedback, or connect with other learners?
• Industry Relevance — Are the concepts updated for current architectures like serverless, containerization, and AI-powered systems?

While not every course passes in every criterion, for example ByteByteGo and Designgurus.io were good on theory and general System Design concepts learning, but they don’t provide an environment to practice System Design questions.

I recommend you combine that with Codemia.io or Bugfree.ai to get the practice and AI mock interview part for complete practice.

Similarly, Exponent was great for mock interviews, but Educative.io and Bugfree.io’s AI mock interviews are also worth trying.

My Top 5 System Design Interview Prep Courses and Platforms for 2026

Without any further ado, here are my top 5 recommendations for learning System Design for technical interviews. These courses and resources are not just to learn general System Design concepts, but also for solving company-specific questions and practicing online.

1. ByteByteGo — System Design Mastery (Premium Pick)

ByteByteGo is my number one recommendation if you want visual, practical, and up-to-date system design learning.

Founded by Alex Xu (author of System Design Interview — An Insider’s Guide), it’s a goldmine of beautifully crafted diagrams, step-by-step explanations, and case studies covering everything from classic designs to modern AI-driven architectures.

Key Features:

• Deep dives into 50+ real-world system architectures
• Updated for 2026 (serverless, edge computing, LLM integrations)
• Animated visuals and flow diagrams
• Weekly new content drops

Perfect For: Engineers who want a premium, all-in-one system design resource that blends theory, visuals, and practice.

They have also done a full website refresh recently as part of their relaunch and added all the content of their 7 best-selling books on System Design, OOP Design, ML System Design, and Generative AI Design on the platform.

They are now also offering 50% discount on their lifetime plan, the one I bought and the one I highly recommend to my students and readers.

Here is the link to join — Get 50% discount

They also provide ByteByteGo 101, a collection of 101 coding questions divided into key coding interview patterns like two pointers, fast and slow pointers, etc., for practice, which makes them the complete package for tech interviews in 2026.

2. Grokking the System Design Interview — DesignGurus.io

The original Grokking course is a favorite for FAANG interview prep. It breaks down system design problems into a clear, repeatable framework so you can approach any interview question with confidence.

Key Features:

• Covers 15+ popular interview problems
• Step-by-step solution walkthroughs
• Includes scalability, fault tolerance, and data partitioning concepts
• Fully interactive coding environment

Perfect For: Engineers focused on nailing system design interviews at top tech companies.

Here is the link to join this course — Grokking the System Design Interview

And, if you like these Grokking interview courses from DesignGurus.io, you can get all of them for a big discount by purchasing their All course bundle.

This bundle includes their most popular Grokking courses like Grokking System Design Interview, OOP Design, Coding Patterns, as well as Grokking Dynamic Programming Interview. You can also use code GURU to get 55% discount now.

3. System Design Masterclass (2026) — Udemy

This Udemy bestseller is taught by FAANG engineers and focuses on practical interview readiness. You’ll work through popular real-world problems while mastering the fundamentals of architecture design.

Key Features:

• 20+ case studies and design walkthroughs
• Covers scalability, APIs, databases, and distributed systems
• Affordable, often available at 80% off during sales
• Lifetime access to all updates

Perfect For: Budget-conscious learners who want high-quality video-based learning from experienced engineers.

Here is the link to join this course — System Design Masterclass (2026)

By the way, Udemy also has many great System Design courses which are worth checking out, like the one from Frank Kane, ex Amazon Hiring Manager, and Sandeep’s System Design course.

And, if you want to join multiple courses on Udemy, it may be worth getting a Udemy Personal Plan, which will give instant access to more than 11,000 top-quality Udemy courses for just $30 a month.

If you have a lot of time and want to save money, Udemy Personal Plan will be perfect for you.

4. System Design Interview Prep — Exponent

Exponent is known for interactive, mock interview-style preparation. Their system design course simulates real interview scenarios, complete with frameworks, whiteboard practice, and peer feedback.

Key Features:

• Live and asynchronous practice sessions
• Feedback from experienced interview coaches
• Video guides and question banks
• Tailored for tech interview success

Perfect For: Engineers who want hands-on interview simulation before stepping into the real thing.

Here is the link to join this course — System Design Interview Prep — Exponent

Another great thing I like about Exponent is their Mock interviews. They provide 5 free mock interviews with peers, which also replenish when you get good feedback. These are great to practice in an interview setting and also learning from peers.

And, if you have any FAANG interviews lined up, then you can also use their FAANG experts to interview for a real test. This is not free, but within $200, you can get a real shot at what to expect at FAANG interviews. I highly recommend them to you if you have an interview with Google, Amazon, or Meta.

I also suggest you get an Exponent subscription to watch this course, which you can get for just $12 a month now (U.P. $79 per month), which is like a 70% discount.

The membership will not only give you access to this course but also to all of their courses, mocks, videos, private community, and AI features for better interview preparation.

5. Grokking the Modern System Design Interview — Educative.io

This one is another great System Design interview course you can join to prepare for FAANG interviews from one of the most interactive learning platforms, Educative.io.

Once you’ve mastered the basics, this course dives deep into complex, large-scale systems — think designing YouTube-scale platforms, AI pipelines, and multi-region deployments.

Key Features:

• Advanced topics like event-driven architecture, CQRS, and Kafka
• Real-world examples from high-scale systems
• Clear diagrams and problem breakdowns

Perfect For: Mid-to-senior engineers looking to level up their architectural thinking.

Here is the link to join this course — Grokking the Modern System Design Interview

Btw, you would need an Educative subscription to join this course, which not only provides access to this course but also more than 1200+ courses to learn essential tech skills, prepare for coding interviews, and improve yourself as a Developer.

If you want to invest in yourself and upgrade your tech skills, this is one subscription you definitely need. They are also offering 60% discount now.

Bonus Recommendations (Bugfree.ai and Books)

Apart from these, Bugfree.ai is another site that caught my attention, and I spent quite a lot of time there.

If you prefer learning by doing rather than just watching videos, Bugfree.ai is a powerful platform to practice System Design in a more hands-on way.

Instead of only consuming theory, you get to actually design systems and receive structured feedback, which makes a big difference when preparing for real interviews.

What makes Bugfree.ai stand out is its AI-assisted evaluation that reviews your design approach, highlights gaps, and suggests improvements — almost like having a mock interviewer available anytime. This is especially useful when you don’t have a study partner or mentor to review your solutions.

Key Features:

• AI feedback on your system design answers
• Real interview-style system design questions
• Focus on structuring answers clearly and covering trade-offs

Perfect For: Engineers who already know the basics and want to sharpen their interview communication and system design thinking through practice.

Here is the link to join —Bugfree.ai (25% OFF)

And, if you want to complement these courses with books, I recommend:

• System Design Interview — An Insider’s Guide by Alex Xu
• Designing Data-Intensive Applications by Martin Kleppmann

These books are timeless references that deepen your understanding of distributed systems and large-scale architecture.

You don’t need too many books; just read these two books in detail, and you will be really well-shapen to answer System design questions in interviews.

Why ByteByteGo Stands Out for System Design Interview Prep?

While all these courses are excellent, ByteByteGo earns my premium pick for three reasons:

1. Visual-First Learning — They have the best visual diagrams on all the topics on System Design, which make even the most complex systems easy to understand.
2. Constant Updates — The platform keeps pace with modern architectures, from microservices to AI integrations. They have now uploaded all the content from their 7 best-selling books on Object Oriented Design, Machine Learning System Design, Gen AI System Design, and even coding patterns and behavioral interviews.
3. Practical Depth — You’re not just learning theory — you’re exploring real-world production systems. Most of their content is written by FAANG engineers who have experience on both sides of the table.

If budget allows, I suggest starting with ByteByteGo for mastery and pairing it with the likes of Codemia.io or Bugfree.ai to get the practice and AI mock interview for best preparation of FAANG interviews in 2026.

They are now also offering 50% discount on their lifetime plan, which means they are now even more valuable, and once you buy their lifetime plan, which is just the cost of a couple of years, you won’t need any resources.

Every time you need to prepare for an interview or just want to stay up to date, you can use the platform.

Here is the link to join — Get 50% discount

They also provide ByteByteGo 101, a collection of 101 coding questions divided into key coding interview patterns like two pointers, fast and slow pointers, etc. I am practicing there now almost every day.

Final Thoughts

That’s my list of the top 5 system design courses for 2026. Whether you’re preparing for a big tech interview, designing complex systems at work, or just looking to level up your architecture skills, these resources will give you the frameworks, knowledge, and confidence to succeed.

• Start with ByteByteGo if you want the best all-around experience
• Add either Codemia.io or Bugfree.ai for structured and live interview practice
• Use books and Designgurus.io to dive deeper into advanced concepts
• Use Exponent for mock interviews with peers(free) and experts (paid)

With consistent study and practice, you’ll be well-prepared to tackle any system design challenge that comes your way in 2026.

All the best with your System Design Interviews. If you have any doubts or questions, feel free to ask in the comments.

P. S. — If you want to do just one thing, then join ByteByteGoand learn System Design Concepts and practice coding interviews, you will thank me later. It’s one of the most comprehensive resources for not just coding interviews but also for senior engineers to get better at their work. They are also offering 50% Discount now.