Status: V1 backend live at api.kradek.com. SDK builds for Windows x64. Linux and macOS next. Free tier opens when BTCPay checkout ships. Email to try it before then.
Ten lines of C++, one afternoon
main.cpp
// 1. Include the header, link Kradek.Licensing.c.lib
#include <kradek/licensing.h>
#include <cstdio>
int main() {
kradek_init("sdk_YOUR_PRODUCT_TOKEN");
// 2. Offline-first: checks a signed token on disk, no network call
kradek_result r = kradek_validate_offline(user_license_key);
if (!r.success) r = kradek_validate_online(user_license_key);
if (!r.success) {
fprintf(stderr, "Invalid license.\n");
return 1;
}
kradek_result_free(&r);
// your app here
}
What you get
One lib. No dependencies.
Static .lib or shared .dll, built with static CRT, zero third-party. No C++ redistributable prompts on your end user's machine.
Offline-first by design.
Every activation returns an ECDSA-signed token stored on disk. Your users keep working through outages and airplane mode for up to seven days with no server call.
Anti-tamper runtime built in.
Pro tier adds guards around the license check itself: anti-patch integrity checks, timing jitter, decoy paths. The license logic is the protection, not a bolt-on.
Full control.
Every machine holding an active slot is visible in your portal. Revoke, transfer, or extend with one click. Webhook events for every license lifecycle change.
Other languages welcome
The C SDK is the primary product. The .NET NuGet is a thin P/Invoke wrapper over it. Any language with a C FFI (Rust bindgen, Go cgo, Python ctypes, Zig) lands the same way. The REST API is also fully documented if you want no dependency at all.
Pricing (flat per vendor, never per seat)
Free
$0
forever
- 1 product
- 50 active licenses
- 1 activation slot
- Licensing module
- Full REST API + SDKs
Live when BTCPay ships
Pro
$19
per month
- 5 products
- 2,000 active licenses
- Up to 10 slots per license
- Basic runtime protection
- Priority webhook retry
Soon
Studio
$49
per month
- 25 products
- 25,000 active licenses
- Unlimited slots
- Advanced runtime protection
- CSV bulk import
Soon
Elite
$99
per month
- Unlimited everything
- Packer (when shipped)
- Priority support
- White-label portal
Soon
Yearly plans get two months free. Themida Pro is $200 one-time and Enterprise starts around $1,000 - Kradek undercuts with a subscription that includes ongoing protection updates.
FAQ
Why not just use Themida?
Themida is excellent and expensive. It also only handles protection; you still need a licensing system. Kradek bundles both, targets solo and small devs, and does not charge per end-user activation.
Will my users need to install anything?
No. The SDK links statically or ships a single DLL alongside your exe. No C++ redistributable, no .NET runtime, no managed code. Static CRT, pure Windows-shipped APIs.
What happens if your server goes down?
Existing users keep working. Every activated machine holds a locally signed ECDSA token valid for however many days you configured (default 7). The offline token is the safety net.
Do you charge per license activation?
No. Your tier price is flat. Create as many licenses and activations as the tier allows. If you outgrow a tier, upgrade. If you outgrow Elite, email us.
Is the license check easy to crack?
By default, a determined cracker can patch any license call out of a binary. That is true for every SDK. Pro adds anti-tamper guards; Elite will ship a binary packer (planned V2) that welds the check into the exe. Serious protection is the point of the paid tiers.
Is the source open?
No. Kradek is a commercial product. SDK headers are visible to customers; backend and runtime protection internals are not.