Things You Can Do With Bun 1.4: The JavaScript Runtime Just Got a Lot More Powerful

There was a time when a JavaScript project needed a surprisingly long package.json.

Need image processing? Install sharp.
Need Markdown? Install a parser.
Need browser automation? Install Playwright or Puppeteer.
Need cron jobs? Add a cron library.
Need pseudo-terminals? Install node-pty.
Need to run scripts concurrently? Install concurrently or npm-run-all.
Need faster tests? Configure workers, shards, and CI tooling.

Bun 1.4 looks at that entire ecosystem and asks a different question on what if the runtime simply did it?

Released on August 20, 2026, Bun 1.4 adds more than 1,500 Node.js compatibility tests, fixes over 2,900 issues, reduces idle CPU usage dramatically, improves memory consumption, and introduces a growing collection of built-in developer tools.

And that’s what makes this release interesting. It’s not just about making JavaScript faster. It’s about making the JavaScript toolchain smaller.

First: Install Bun

--curl
curl -fsSL https://bun.sh/install | bash

--npm
npm install -g bun

--brew
brew install oven-sh/bun/bun

--powershell
powershell -c "irm bun.sh/install.ps1 | iex"

--docker
docker pull oven/bun

If you’re already using Bun, upgrading is almost embarrassingly simple:

bun upgrade

That’s it.

Now let’s look at what you can actually do with Bun 1.4.

1. Process Images Without Installing `sharp`

Image processing is now part of Bun itself through Bun.Image.

You can decode, resize, rotate, and encode common image formats without installing a native image-processing dependency.

await Bun.file("photo.jpg")
  .image()
  .resize(1024, 1024, { fit: "inside" })
  .rotate(90)
  .webp({ quality: 85 })
  .write("thumb.webp");

That opens up some interesting possibilities:

Generate thumbnails during uploads
Resize user avatars
Convert JPEG → WebP
Build image-processing APIs
Optimize assets before storage
Create server-side image pipelines

Bun says its implementation is faster than sharp in several tested transformations, including a 1080p PNG resize/encode benchmark.

The bigger win isn’t just speed. It’s fewer dependencies.

2. Automate Browsers Without Puppeteer

Bun 1.4 also gives you Bun.WebView.

It’s a built-in headless browser automation API capable of navigation, clicking, scrolling, JavaScript evaluation, and screenshots.

await using view = new Bun.WebView({
  width: 800,
  height: 600,
});

await view.navigate("https://bun.sh");
await view.click("a[href='/docs']");
const title = await view.evaluate("document.title");
await Bun.write(
  "page.png",
  await view.screenshot()
);

Think about what this means for small automation projects.

You could build:

Website screenshot generators
Automated webpage testing
Scraping utilities
Browser-based monitoring
Link checking tools
Simple QA automation

And you don’t necessarily need to start by installing another browser automation framework.

For more advanced browser control, Bun.WebView also exposes a Chrome DevTools Protocol escape hatch.

3. Turn Markdown Into HTML, React, or Terminal Output

Bun 1.4 includes Bun.markdown.

You can transform Markdown into HTML:

const html = Bun.markdown.html(
  "# Hello **world**"
);

You can also turn Markdown into React elements:

export default function Page() {
  return Bun.markdown.react(readme);
}

Or customize rendering for things such as terminal output.

This is surprisingly useful for developers building:

Documentation platforms
Developer portals
Markdown-based blogs
README viewers
CLI documentation
Knowledge bases
AI-generated Markdown interfaces

Bun also supports GitHub-Flavored Markdown features such as tables, task lists, strikethrough, and autolinks.

One important security detail: the generated HTML isn’t sanitized automatically.

If you’re rendering untrusted Markdown, you still need an appropriate sanitization layer.

4. Schedule Jobs With `Bun.cron()`

Here’s another dependency you may no longer need.

Bun 1.4 includes Bun.cron().

It can register operating-system-level scheduled jobs using:

crontab on Linux
launchd on macOS
Task Scheduler on Windows

For example:

await Bun.cron(
  "./worker.ts",
  "30 2 * * MON",
  "weekly-report"
);

You can also run cron jobs directly inside the process:

using job = Bun.cron(
  "*/5 * * * *",
  async () => {
    await cleanupTempFiles();
  }
);

Jobs don’t overlap, and Bun supports explicit time zones.

That makes Bun surprisingly useful for building:

Cleanup workers
Scheduled reports
Database maintenance
Data synchronization
Email jobs
Background processing
Periodic API polling

A JavaScript runtime that can schedule its own work is a very different runtime from the one we started with.

5. Run Multiple Scripts in Parallel

Remember installing concurrently or `npm-run-all?

Bun now has:

bun run --parallel build test

You can also use patterns:

bun run --parallel "build:*"

And workspaces:

bun run --parallel --filter '*' build

You can even continue running other tasks when one fails:

bun run --parallel --no-exit-on-error --filter '*' test

Bun prefixes the output with the relevant script name, making concurrent output much easier to understand.

For monorepos, this is particularly useful.

Instead of:

package A → build
package B → build
package C → build

you can fan the work out across your machine.

💡 Enjoying this article?
Every week day, I publish practical, production-ready deep dives covering Web development, System Design, Open source projects, Tech industry trends and AI Engineering and tools.

Subscribe to Newsletter

6. Make Your Test Suite Seriously Faster

This is one of my favorite changes.

Bun 1.4 adds:

bun test --parallel

Tests can run across multiple worker processes:

bun test --parallel=4

Bun dynamically distributes test files between workers rather than simply assigning a fixed number to each worker.

Bun also adds several useful testing capabilities:

bun test --shard=1/3

Split a test suite across CI machines.

bun test --changed

Run only tests affected by your changes.

bun test --timings=timings.json

Use previous test durations to distribute work more intelligently.

This is where Bun starts feeling less like “a fast Node alternative” and more like a complete development environment.

7. Fix Vulnerable Dependencies

Security maintenance also gets a built-in workflow.

Run:

bun audit fix

Bun can upgrade vulnerable packages to safe versions and install the changes. If the fix requires a major version change, Bun can tell you about it, while --latest can opt into those upgrades.

For CI pipelines, this is particularly useful because dependency security doesn’t need to be another completely separate workflow.

8. Remove Duplicate Dependencies

Large JavaScript projects often end up with dependency duplication.

For example:

[email protected]
[email protected]

If one version can satisfy both dependency requirements, Bun can consolidate them:

bun dedupe

And:

bun dedupe --check

can be used to make CI fail when duplicates remain. This matters more than it sounds.

Fewer duplicate dependencies can mean:

Smaller dependency trees
Less installation overhead
Less disk usage
Simpler dependency management
Potentially smaller deployments

9. Use a Built-in Terminal

Bun 1.4 also includes Bun.Terminal. It’s a built-in pseudo-terminal that lets JavaScript interact with programs such as:

bash
vim
htop

without depending on node-pty.

This is particularly interesting for:

Developer tools
CLI applications
AI coding agents
Interactive automation
Terminal-based dashboards
Remote development tools

And considering how quickly AI coding agents are becoming terminal-native, this capability could become increasingly important.

10. Run Next.js and Modern Node Ecosystem Apps

Perhaps the most important improvement isn’t a new API at all.

It’s compatibility.

Bun 1.4 adds 1,517 Node.js tests and reports significant compatibility improvements across modules such as http, fs, stream, cluster, timers, zlib, vm, and others.

The release also highlights compatibility improvements for projects and tools including:

Next.js 16
Playwright
Vitest
OpenTelemetry
Datadog dd-trace
Fastify
TypeORM
RabbitMQ clients
AWS S3 clients
Nuxt
Testcontainers

For example:

bun --bun next build

works with Next.js 16.3, Turbopack, and the React Compiler. That’s important because runtime adoption isn’t really about benchmarks.

It’s about whether your existing application survives the migration.

11. Get Better Production Performance

And yes, Bun still brings the performance story.

According to Bun’s benchmarks, version 1.4 reduces idle CPU usage by up to 5× and significantly reduces memory usage in HTTP workloads. It also starts substantially faster on Linux and Windows.

For example, Bun reports:

These are Bun’s own benchmark results, so treat them as directional rather than universal application guarantees.

Still, the direction is impressive.

Less CPU + less memory + faster startup = cheaper and more responsive services.

So, What Should Developers Actually Do With Bun 1.4?

If you’re experimenting with Bun, don’t migrate your entire production system tomorrow.

Start smaller.

Try it for a new API

bun init

Build a small API with Bun.serve.

Try image processing

Replace a small sharp workflow with Bun.Image.

Try scheduled jobs

Move one simple cron task to Bun.cron().

Try parallel testing

bun test --parallel

Try dependency maintenance

bun audit fix
bun dedupe

Try it with your existing Next.js project

bun --bun next build

Measure the results instead of trusting benchmarks blindly.

The Bigger Picture

Bun 1.4 isn’t really about adding ten shiny APIs.

The interesting trend is consolidation.

One runtime is gradually absorbing responsibilities that historically belonged to separate packages:

Bun 1.4
               │
     ┌─────────┼──────────┐
     │         │          │
 Runtime    Tooling    Libraries
     │         │          │
 Node.js     Testing    Image
 APIs        Scripts    Markdown
             Security   Browser
             CI         Cron
             Terminal

That’s the real story.

The JavaScript ecosystem became powerful partly because we could compose thousands of packages.

But that power came with a cost: dependencies, configuration, compatibility issues, security updates, tooling fragmentation, and increasingly complicated build pipelines.

Bun is taking the opposite approach. Put more useful primitives directly into the runtime and in v1.4, it pushes that idea considerably further.

If you’re a JavaScript or TypeScript developer, this is probably the right time to stop asking “Is Bun faster than Node?” and start asking “How much of my development stack can Bun replace?”

That’s a much more interesting question.

Reference: Official Bun 1.4 announcement

Thank You for Reading!

I hope you found it helpful and informative. If you have any questions or feedback, feel free to leave a comment below. Your support and engagement mean a lot to me.

Things You Can Do With Bun 1.4: The JavaScript Runtime Just Got a Lot More Powerful

First: Install Bun

1. Process Images Without Installing `sharp`

2. Automate Browsers Without Puppeteer

3. Turn Markdown Into HTML, React, or Terminal Output

4. Schedule Jobs With `Bun.cron()`

5. Run Multiple Scripts in Parallel

6. Make Your Test Suite Seriously Faster

7. Fix Vulnerable Dependencies

8. Remove Duplicate Dependencies

9. Use a Built-in Terminal

10. Run Next.js and Modern Node Ecosystem Apps

11. Get Better Production Performance

So, What Should Developers Actually Do With Bun 1.4?

Try it for a new API

Try image processing

Try scheduled jobs

Try parallel testing

Try dependency maintenance

Try it with your existing Next.js project

The Bigger Picture

Thank You for Reading!

Happy Coding!

Reply

Keep Reading

Vijayasekhar Deepak | FullStack JS & AI Newsletter

Things You Can Do With Bun 1.4: The JavaScript Runtime Just Got a Lot More Powerful

First: Install Bun

1. Process Images Without Installing sharp

2. Automate Browsers Without Puppeteer

3. Turn Markdown Into HTML, React, or Terminal Output

4. Schedule Jobs With Bun.cron()

5. Run Multiple Scripts in Parallel

6. Make Your Test Suite Seriously Faster

7. Fix Vulnerable Dependencies

8. Remove Duplicate Dependencies

9. Use a Built-in Terminal

10. Run Next.js and Modern Node Ecosystem Apps

11. Get Better Production Performance

So, What Should Developers Actually Do With Bun 1.4?

Try it for a new API

Try image processing

Try scheduled jobs

Try parallel testing

Try dependency maintenance

Try it with your existing Next.js project

The Bigger Picture

Thank You for Reading!

Happy Coding!

Reply

Keep Reading

Vijayasekhar Deepak | FullStack JS & AI Newsletter

1. Process Images Without Installing `sharp`

4. Schedule Jobs With `Bun.cron()`