# Bypass Kasada

 94% success on Kasada-blocked targets. One API parameter.

##  PoW solved once. `kas_challenge` replayed. Session cached. 

- **Real browser fingerprints.** [TLS](https://scrapfly.io/web-scraping-tools/ja3-fingerprint), [HTTP/2](https://scrapfly.io/web-scraping-tools/http2-fingerprint), [Canvas](https://scrapfly.io/web-scraping-tools/canvas-fingerprint), and [WebGL](https://scrapfly.io/web-scraping-tools/webgl-fingerprint) all match real Chrome on every request.
- **Adaptive challenge solving.** [JavaScript execution](https://scrapfly.io/docs/scrape-api/javascript-rendering), CAPTCHAs, proof-of-work, handled without solver keys.
- **Session intelligence.** Unblocked browser sessions reused across requests so Kasada sees a single coherent visitor.
 
**One API parameter.** Add `asp=True`. See the [ASP docs](https://scrapfly.io/docs/scrape-api/anti-scraping-protection).

 [Get Free API Key](https://scrapfly.io/register) [Read ASP docs](https://scrapfly.io/docs/scrape-api/anti-scraping-protection) 

 1,000 free credits. No credit card required. 

 

   

 FINGERPRINT DATA  LIVE  

















 

 

 + 4,000 more datapoints... 

 

 4,000+

 Fingerprint Datapoints 

200M+

 Proxy IPs 

50+

 Anti-Bots 

 



 

 

 

 

 

---

 COVERAGE## Every Kasada Signal, Matched

Bit-for-bit fingerprint parity with real Chrome. Not monkey-patching, not surface-level, engineered at the protocol and C++ layers.

 

 ##### kas.js Puzzle Solved. kas\_challenge Token Signed.

Kasada forces every first-time visitor to solve a proof-of-work puzzle in the browser. The puzzle is cheap for a real browser and expensive in aggregate for a botnet. On top, the `kas.js` collector reads fingerprint + behavioral signals and emits a signed `kas_challenge` token. Scrapfly solves both inside Scrapium once, then reuses the unblocked session so the cost per page stays predictable.

**94%**success on kasada

**kas.js**collector payload valid

**kas\_challenge**PoW token signed

**1,000+**sites behind kasada

 





 

 

 ##### Proof-of-Work + kas\_challenge

Kasada's PoW runs in a web worker; the answer is cryptographically signed into `kas_challenge` and attached via `x-kasada-*` headers. Without matching TLS + browser fingerprint, the token is rejected even if the PoW math is correct.

PoW worker

kas\_challenge

x-kasada headers

\_\_kasada object

 

 





 ##### Why DIY Bypasses Fail

Solving the PoW math alone gets you nowhere, the collector payload still has to verify.

 | **curl-impersonate** | no kas.js execution |
|---|---|
| **kasada-bypass (OSS)** | abandoned per rotation |
| **Playwright + stealth** | collector leaks |
| **Selenium** | timing signals off |
| **Scrapfly** | 94%, tracked daily |

 





 

 ##### PoW Caching

Scrapfly solves once, caches the unblocked session, reuses across requests. Bot PoW cost amortizes to ~free.

 **once** solve per session 

 





 ##### Device Fingerprint, C++ Patches

Kasada reads Canvas, WebGL, AudioContext, Navigator, and timing signals. Scrapium patches each at Chromium source level, JS-hook detection via `toString()` sees native bindings.

[Canvas](https://scrapfly.io/web-scraping-tools/canvas-fingerprint)

[WebGL](https://scrapfly.io/web-scraping-tools/webgl-fingerprint)

[Audio](https://scrapfly.io/web-scraping-tools/audio-fingerprint)

Navigator

Timing

Plugins

 

 





 ##### Scalper Pressure

Kasada is heavy on sites under active scalper pressure: concert tickets, sneaker drops, gaming.

- Ticketing
- Sneakers
- Gaming
 
 





 

 ##### Kasada Detection Stack, Every Layer Matched

Kasada chains TLS → kas.js collector → PoW worker → kas\_challenge token → `x-kasada-*` header validation. Fail one, block follows.

 **TLS + HTTP/2**Chrome wire format at edge

 

 **kas.js Collector**payload signed under real Chrome

 

 **Proof-of-Work**solved once, unblocked session cached

 

 **kas\_challenge Token**x-kasada-\* headers replayed coherently

 

 

 





 ##### TLS + kas.js Collector

Kasada fingerprints TLS at the edge and cross-checks the `kas.js` collector payload server-side.

- JA4 match, Chrome-identical
- HTTP/2 SETTINGS aligned
- Collector payload signed valid
- Behavioral signals coherent
 
 





 

 

---

 REVERSED## What The Kasada Sensor Actually Collects

Kasada builds every probe name at runtime inside its own bytecode interpreter, so reading the script tells you nothing. We record a passing session with VisibleV8, a Chromium build that logs every property read with its exact arguments, which is the only way this surface is observable at all.

 

 ##### Nothing To Grep

Kasada ships a large obfuscated payload that decodes into a custom bytecode VM. Of the probe names it uses, none appear as readable strings in the file. Static analysis of the sensor returns nothing useful, which is exactly the point.

0probe names visible statically

**100%**built at runtime by the VM

 

 



 

 ##### It Hunts Your Tooling By Name

Beyond the usual canvas, audio and codec fingerprints, Kasada walks the window and navigator prototypes looking for the specific automation stack you are running.

 | **Automation frameworks** | checks for Playwright, Electron and embedded-browser markers by name |
|---|---|
| **Headless DOM internals** | probes for the private fields a simulated DOM leaves behind |
| **CAPTCHA solvers** | looks for the global functions popular auto-solver extensions inject |
| **Extension presence** | queries the extension runtime bridge on the challenge path |
| **Pristine natives** | opens an iframe to recover untouched native functions, reading `contentWindow` hundreds of times |
| **Font descriptors** | enumerates fonts through the FontFace API rather than by measuring text |

Scrapium carries no automation markers to find, because the automation lives in the C++ layer rather than in an injected script.

 



 

 

 

---

 PROOF## One Parameter. Kasada Cleared.

Add `asp=True`. Scrapfly detects Kasada and routes through the correct engine, Curlium for HTTP-layer targets, Scrapium for JS-heavy ones.

 

Set `asp=True` and Scrapfly handles Kasada automatically. Picks [Curlium](https://scrapfly.io/curlium) or [Scrapium](https://scrapfly.io/scrapium) per target.

     Python TypeScript Go Rust HTTP / cURL  

      

 ```
from scrapfly import ScrapeConfig, ScrapflyClient, ScrapeApiResponse
client = ScrapflyClient(key="API KEY")

api_response: ScrapeApiResponse = client.scrape(
    ScrapeConfig(
        url='https://httpbin.dev/html',
        # enable Scrapfly ASP mode
        asp=True
    )
)
print(api_response.result)
```

 ```
import { 
    ScrapflyClient, ScrapeConfig 
} from 'jsr:@scrapfly/scrapfly-sdk';

const client = new ScrapflyClient({ key: "API KEY" });
let api_result = await client.scrape(
    new ScrapeConfig({
        url: 'https://httpbin.dev/html',
        // enable Scrapfly ASP mode
        asp: true,
    })
);
console.log(api_result.result);
```

 ```
package main

import (
	"fmt"
	"github.com/scrapfly/go-scrapfly"
)

func main() {
	client, _ := scrapfly.New("API KEY")
	result, _ := client.Scrape(&scrapfly.ScrapeConfig{
		URL: "https://httpbin.dev/html",
		// enable Scrapfly ASP mode
		ASP: true,
	})
	fmt.Println(result.Result.Content)
}
```

 ```
use scrapfly_sdk::{Client, ScrapeConfig};

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let client = Client::builder().api_key("API KEY").build()?;

    let cfg = ScrapeConfig::builder("https://httpbin.dev/html")
        // enable Scrapfly ASP mode
        .asp(true)
        .build()?;

    let result = client.scrape(&cfg).await?;
    println!("{}", result.result.content);
    Ok(())
}
```

 ```
http https://api.scrapfly.io/scrape \
key==$SCRAPFLY_KEY \
url==https://httpbin.dev/html \
asp==true
```

 

 

 // RESPONSE    json  

 ```
{
  "result": {
    "status_code": 200,
    "success": true,
    "url": "https://httpbin.dev/html",
    "content": "<html>...</html>",
    "content_format": "raw",
    "content_type": "text/html; charset=utf-8",
    "response_headers": {
      "content-type": "text/html; charset=utf-8",
      "server": "nginx"
    },
    "cookies": [],
    "duration": 1842,
    "log_url": "https://scrapfly.io/dashboard/monitoring/log/01J...",
    "asp_cost": 30
  },
  "context": {
    "asp": true,
    "proxy": {
      "country": "us",
      "type": "datacenter"
    }
  }
}
```

 

 

 

 [ Python SDK docs → ](https://scrapfly.io/docs/sdk/python) [ TypeScript SDK docs → ](https://scrapfly.io/docs/sdk/typescript) [ Go SDK docs → ](https://scrapfly.io/docs/sdk/golang) [ Rust SDK docs → ](https://scrapfly.io/docs/sdk/rust) [ HTTP API docs → ](https://scrapfly.io/docs) 

 

 

 [ Get Free API Key ](https://scrapfly.io/register) [ Read the Bypass Guide → ](https://scrapfly.io/blog/posts/how-to-bypass-kasada-anti-scraping-waf) 

 

---

  FAQ## Frequently Asked Questions

 

  ### Can I test on my specific Kasada targets?

 Yes. The free plan includes 1,000 API credits with no credit card required. Enable `asp=True` and test your exact targets before committing. Scrapfly achieves 94% success on Kasada-blocked sites; failed requests are not charged.

 

   ### How much does ASP cost?

 ASP starts at 30+ credits per request, scaling with target complexity. You pay for what a specific target needs, not a flat premium. See [pricing](https://scrapfly.io/pricing).

 

   ### What is Kasada's proof-of-work?

 Kasada forces every first-time visitor to solve a computational puzzle in the browser before the real response is served. The puzzle is short for a real browser and expensive in aggregate for a botnet. Scrapfly solves the puzzle inside Scrapium then reuses the unblocked session, so the cost per page stays predictable. DIY guide: [bypassing Kasada](https://scrapfly.io/blog/posts/how-to-bypass-kasada-anti-scraping-waf).

 

   ### Where is Kasada deployed?

 Ticketing, gaming, and e-commerce. Kasada is particularly common on sites under active scalper pressure, concerts, sneaker drops, online gambling. The kas.js collector runs on every page and produces a signed kas\_challenge token that must match the HTTP request.

 

  

 

  ---

 // SEE ALSO### Bypass every other major anti-bot vendor too.

ASP handles every major anti-bot stack with the same flag. Switch targets, keep the parameter.

 [Cloudflare](https://scrapfly.io/bypass/cloudflare) 

 [Akamai](https://scrapfly.io/bypass/akamai) 

 [DataDome](https://scrapfly.io/bypass/datadome) 

 [PerimeterX](https://scrapfly.io/bypass/perimeterx) 

 [Incapsula](https://scrapfly.io/bypass/incapsula) 

 [F5](https://scrapfly.io/bypass/f5) 

 [AWS WAF](https://scrapfly.io/bypass/aws-waf) 

 

 

 [Get Free API Key](https://scrapfly.io/register) [View all anti-bot bypasses](https://scrapfly.io/bypass)