01API
Readable by design
Shield.When<TimeoutException>().Retry(3) reads like intent, not infrastructure. Use concise defaults or take full control with options objects.
One shield. Every failure mode.
RetryCircuit breakerTimeoutRate limitConcurrency limitHedgingFallback
Engineered differentlyLess framework.
Less framework.
More resilience.
Kevlar strips away accidental complexity without giving up the control, performance or observability production systems need.
02100 ns
Built for the hot path
Struct outcomes, pooled contexts, state-passing overloads and ValueTask end to end keep successful calls fast and allocation-free.
03SAFE
Defaults you can ship
Shield.Retry(3) includes exponential backoff with jitter, capped at 30 seconds—the production setting you wanted anyway.
04FLUENT
Composition, not ceremony
Chain strategies fluently. Merge shields with Wrap and Compose. Reuse one instance when state should be shared.
050 DEPS
Nothing hiding underneath
Core Kevlar depends on nothing but the BCL. No surprise transitive packages, version conflicts or dependency-tree baggage.
06.NET
Old apps. New apps.
Targets netstandard2.0 and net8.0, with integrations for Microsoft DI and HttpClientFactory.
Measured, not marketedTiny overhead.
Tiny overhead.
Serious protection.
100 ns
Successful Retry(3) execution
0 B
Allocated on the happy path
0 deps
In the core package
Designed for intentProtection that
Protection that
reads like code.
Build complete resilience pipelines from focused strategies. Sensible defaults keep common cases concise; options objects give you full control when you need it.
KevlarSensible defaults
var shield = Shield
.Timeout(TimeSpan.FromSeconds(30))
.Retry(3)
.CircuitBreaker(5,
breakDuration: TimeSpan.FromSeconds(30));
Timeout · Retry · Circuit breakerOne fluent API
KevlarFull control
var search = Shield.For<HttpResponseMessage>()
.When<HttpRequestException>()
.OrResult(r => (int)r.StatusCode is >= 500 or 429)
.Fallback((outcome, ct) => cache.GetCachedAsync(ct))
.Retry(o =>
{
o.MaxRetries = 4;
o.DelayGenerator = e =>
e.Outcome.Result?.Headers.RetryAfter?.Delta;
o.OnRetry = e => logger.LogWarning(
"retry {Attempt} in {Delay}", e.Attempt, e.Delay);
})
.CircuitBreaker(o =>
{
o.FailureRatio = 0.5;
o.SamplingWindow = TimeSpan.FromSeconds(30);
o.Monitor = monitor;
})
.Hedge(maxAttempts: 2, delay: TimeSpan.FromMilliseconds(150))
.Timeout(TimeSpan.FromSeconds(2))
.WithName("search");
Typed results · Retry-After · Hedging · FallbackSame fluent API
Ready for impact
Get started