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ALTCHA
ALTCHA Solver
Bypass the ALTCHA proof-of-work CAPTCHA on your own machine. CapSkip computes the challenge in milliseconds and hands back the token the form expects, with unlimited solves at one flat price.
Windows x64·Runs locally, so no CAPTCHA leaves your machine
- Unlimited solving
- Solves in milliseconds
- Deterministic, never a guess
ALTCHAs a month6,000
6.0k250.0k
$7.94stays in your pocketevery month, at this volume
CapSkip is a desktop ALTCHA solver that runs the proof of work on your own Windows machine or VPS. Give it the challenge document, or just the URL the ALTCHA widget fetches it from, and CapSkip finds the number that satisfies the challenge and returns the payload the hidden altcha field expects. Nothing goes to a remote solving farm, and because the answer is computed rather than recognised, an ALTCHA solve is deterministic: it either finds the answer or the challenge itself was malformed or expired.
Per-solve services such as 2Captcha, Anti-Captcha and SolveCaptcha bill you for every 1,000 ALTCHA solves even though the work is a few milliseconds of CPU. CapSkip is unlimited flat-rate instead: Bronze $10/mo, Silver $17/mo, Gold $20/mo, plus a $99 one-time lifetime license, each with unlimited solving and unlimited threads. Retry a challenge that expired mid-queue as often as you like, because nothing here is metered.
CapSkip reads the challenge and picks the algorithm itself, so you never have to work out which generation a site is running. The older scheme, which is the shape every commercial solving service sells today, is covered with SHA-1, SHA-256, SHA-384 and SHA-512, and the current Proof-of-Work v2 scheme is covered with PBKDF2 and iterative SHA, the default ALTCHA itself recommends. All three widget styles, native, checkbox and switch, submit the same payload, so all three are solved. Argon2id and scrypt are refused cleanly in about a third of a second rather than attempted. Use it through the no-code Chrome and Firefox extension, the official Python, Node.js, PHP and .NET SDKs, or a local HTTP API that speaks both the 2Captcha and Anti-Captcha ALTCHA shapes, so an existing integration usually needs no code changes.
No coding required. Run the CapSkip app and the browser extension connects automatically, then solves CAPTCHAs right in the page. Already using another service? Migrating is easy: CapSkip is a drop-in captcha solver that emulates 2Captcha, RuCaptcha, Anti-Captcha, CapMonster Cloud, CapSolver, DeathByCaptcha, SolveCaptcha and Captchas.io. Add your service to the hosts file in the CapSkip app and your existing code is routed to CapSkip and solved locally, with no changes.
Why CapSkip is the best ALTCHA solver
Unlimited ALTCHA solves, flat price
A $99 one-time lifetime license plus a subscription from $10/mo. No credits to top up and no per-token billing, so a retry costs nothing and volume never changes the bill.
Milliseconds, not seconds
ALTCHA is CPU work rather than a browser session, so a typical challenge clears in milliseconds. Throughput is bounded only by the cores on your own machine.
Deterministic, never a guess
There is no image to read and no model to be wrong, so there is no accuracy rate to worry about. CapSkip either finds the number that satisfies the challenge or tells you the challenge could not be solved.
Local and private
Send the challenge document and CapSkip makes no network request at all while solving. The challenge, the page URL and the answer never leave your machine.
Both ALTCHA generations
Legacy SHA-1, SHA-256, SHA-384 and SHA-512, plus Proof-of-Work v2 with PBKDF2 or iterative SHA. CapSkip detects which one it was handed and picks the algorithm for you.
Drop-in API emulation
Point an existing ALTCHA integration at CapSkip and keep your code. Both the 2Captcha legacy form API (method=altcha on in.php) and the Anti-Captcha JSON task (AltchaTaskProxyless) work as they are.
Three ways to solve ALTCHA
from capskip import CapSkip
solver = CapSkip(host="127.0.0.1", port=8080)
# Point CapSkip at the endpoint the ALTCHA widget fetches its challenge from,
# or pass challenge_json= if you already hold the document itself.
result = solver.altcha(
url="https://example.com/register",
challenge_url="https://example.com/altcha/challenge",
)
# result["token"] goes straight into the hidden "altcha" form field.
print(result["token"], result["number"])Solve an ALTCHA proof-of-work challenge in a few lines with the CapSkip Python SDK.
No-code browser extension
Install the CapSkip extension and it detects the widget on any page and solves it for you, with nothing to script.
Official SDKs
Automate solving from your own code with the Python, Node.js, PHP and C# clients. A few lines returns a valid token.
Local HTTP API
Prefer raw HTTP? CapSkip exposes a local endpoint with 2Captcha and Anti-Captcha API emulation, so any HTTP client works.
How to solve ALTCHA with CapSkip
-
1
Install CapSkip
Download the desktop app for Windows (or run it on a VPS) and launch it. The local solver starts automatically.
-
2
Sign in to the app
Buy the $1 trial or a Bronze / Silver / Gold license and your login details arrive by email straight away, with the license live the moment you pay. Sign in to the app with them and you are ready to solve. The setup guide walks through it.
-
3
Solve automatically
Use the browser extension for no-code solving, or call the SDK / HTTP API from your automation.
CapSkip vs per-solve ALTCHA services
| Feature | CapSkip | Per-solve services |
|---|---|---|
| Pricing model | Flat unlimited ($99 one-time, then $10/mo) | Billed per 1,000 ALTCHA solves |
| Where solving runs | Locally on your Windows machine or VPS | Remote servers you send the challenge to |
| Speed | Milliseconds of local CPU, no round trip | Network round trip plus queue time |
| Privacy | Challenge and page URL stay on your machine | Challenge and page URL sent to a third party |
| Retries | Free, because solving is not metered | Every attempt is another billed solve |
| Throughput | Unlimited threads, bounded only by your cores | Queue-based, subject to worker availability |
| Integration | No-code extension, SDKs, or drop-in API emulation | API only, per-service client code |
Pricing
Stop paying per solve
Per-solve services bill you for every single challenge, forever. CapSkip bills one flat monthly rate and solves as many as your hardware can take. Here is what that difference is worth at your volume.
100KCAPTCHAs a month
20K2M
Mostly which types
Blended at $2.99 per 1,000 solves.
A per-solve service$299.00
every month, and it rises with every solve
CapSkip, flat$10.00
every month, whatever the volume
That is $289.00 a month you stop spending.
Year one: $3,588 on a per-solve service against $219 here.
Choose your license
Bronze License
$10/ month
+ $99 one-time licenseyours to keep
Subscribe to BronzeInstant license activation
Cancel the monthly whenever you like; the license stays yours.
All three licenses are the same product.
Bronze, Silver and Gold differ by one thing only: how many machines you run it on.
- Unlimited solving, no daily cap
- Unlimited threads, speed scales with your hardware
- 90% to 100% recognition accuracy
- Drop-in replacement for the major solving service APIs
- Works with almost any tool, no coding required
- REST API, SDKs and a browser extension
- Free training when a new CAPTCHA type appears
- Runs on your machine, nothing leaves it
Every CAPTCHA type CapSkip solves is on every license. See the coverage band
Just want to try it first?
Start with a 7-day trial for $1 and solve 1,000 CAPTCHAs of any type on your own targets.
How to bypass ALTCHA proof of work
Start with the challenge. Open DevTools on the target page and watch the request the altcha-widget element makes for its challenge, often something like /altcha/challenge. The request URL is what you pass to CapSkip as challenge_url, and the JSON response is what you pass as challenge_json. Older widgets name that endpoint in a challengeurl attribute; widget v3 dropped it, and its single challenge attribute holds either a URL or the challenge data, so read the page source rather than assuming. Send either one to CapSkip through the Python, Node.js, PHP or .NET SDK, or through the local 2Captcha-compatible HTTP API, and it returns the payload to write into the hidden altcha field before you submit the form. Give it challenge_json and it solves with no network request at all; give it challenge_url and it fetches the challenge for you, through your own proxy if you pass one.
The most common reason a correct answer is rejected is expiry, not a bad solve. A legacy challenge carries its deadline inside the salt and a Proof-of-Work v2 challenge declares it as expiresAt, and the windows are short: some sites issue challenges that are valid for barely two minutes. So fetch the challenge immediately before solving and post the token promptly, rather than collecting challenges in advance or holding one while a user fills in a form. CapSkip helps on both sides: an inline challenge that has already expired is refused straight away instead of burning CPU on a token that cannot work, and a challenge URL is refetched automatically when the original expired while the task was queued.
Migrating an existing integration takes no code changes. CapSkip answers the 2Captcha legacy form API with method=altcha on in.php, which is what the 2Captcha, RuCaptcha, SolveCaptcha and Captchas.io clients send, and the Anti-Captcha style JSON task AltchaTaskProxyless on createTask, which is what the Anti-Captcha, CapMonster and CapSolver clients send. Add the service to the hosts file in the CapSkip app and your current ALTCHA code is routed to your own machine and solved locally. If you would rather not write code at all, the Chrome and Firefox extension handles ALTCHA in the page for you.
What is an ALTCHA solver?
An ALTCHA solver completes the proof-of-work challenge an ALTCHA widget issues: it searches for the number that satisfies the challenge and returns the payload the form submits. CapSkip does that locally on your own machine, in milliseconds, with unlimited flat-rate pricing.
How do I bypass ALTCHA?
Grab the challenge the widget fetches, pass it to CapSkip as challenge_url or challenge_json through an SDK or the local HTTP API, and write the token it returns into the hidden altcha field before submitting. The Chrome and Firefox extension does the same thing in-page with no code.
Does ALTCHA have images or puzzles to recognise?
No. ALTCHA is not a recognition CAPTCHA: there is no image, audio or text to read. The site issues a challenge and the browser has to find a number that satisfies it by brute force, and that CPU cost is the whole defence. That is why an ALTCHA solve has no accuracy rate, only a result.
Which ALTCHA algorithms does CapSkip support?
The legacy scheme with SHA-1, SHA-256, SHA-384 and SHA-512, and Proof-of-Work v2 with PBKDF2 (SHA-256/384/512) or iterative SHA, which is the default ALTCHA recommends. Argon2id and scrypt are refused cleanly rather than attempted, so a task using one fails fast instead of running up CPU.
How fast is ALTCHA solving?
Typically milliseconds, because the work is local CPU rather than a browser session or a queue on a remote server. Concurrency is limited only by your own core count, since each busy thread can saturate a core.
Can I solve ALTCHA in Python?
Yes. Install the SDK with pip install capskip and call solver.altcha(url=..., challenge_url=...), or call the 2Captcha-compatible local API with any HTTP client. The Node.js, PHP and .NET SDKs expose the same method, and there is an MCP tool for AI agents.
Why is my ALTCHA token rejected even though it solved?
Almost always because the challenge expired. Sites refuse a late solution with a bare verification failure that looks exactly like a wrong answer, and some issue challenges valid for barely two minutes. Fetch the challenge immediately before solving and submit promptly, or pass a challenge URL so CapSkip can refetch a fresh one.
How much does an ALTCHA solver cost?
CapSkip is flat-rate and unlimited from $10/mo, plus a $99 one-time lifetime license, instead of per-1,000 ALTCHA billing from 2Captcha, Anti-Captcha or SolveCaptcha. A $1 trial covers 1,000 solves of any type over 7 days.
Can I keep my existing 2Captcha or Anti-Captcha ALTCHA code?
Yes. CapSkip answers both ALTCHA shapes: the 2Captcha legacy form API (method=altcha on in.php) and the Anti-Captcha style JSON task (AltchaTaskProxyless on createTask). Route your service through the hosts file in the app and the same code solves locally.
Does the browser extension solve ALTCHA without coding?
Yes. The extension catches the challenge the widget fetches, has the local app solve it, then lets the widget assemble its own payload from the answer, so the widget ends up genuinely verified rather than holding a pasted string.
Ready to solve ALTCHA?
Download CapSkip, activate a license, and solve unlimited ALTCHA challenges from your browser or from your code. One flat price, no per-solve billing.
