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When request logging is enabled, the Apitally SDK captures details about each request and response handled by your application. To protect sensitive data and reduce noise, the SDK provides mechanisms for masking data and filtering out requests you don’t want to log.

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Default masking and exclusion

The SDK automatically masks common sensitive query parameters, headers, and request/response body fields based on built-in patterns. For example, fields named password, token, secret, or headers like Authorization are masked by default. To reduce noise, the SDK also automatically excludes common static assets and health check endpoints, such as /robots.txt or /healthz. See the data privacy page for complete lists of default masking and exclusion patterns.

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Mask sensitive data

You can extend the default masking rules by providing additional regular expressions via the QueryParamMaskPatterns, HeaderMaskPatterns, and BodyFieldMaskPatterns properties. Patterns are case-insensitive and match anywhere within the name. Use ^ and $ anchors for exact matches. For more control over request and response body masking, you can provide callback functions via the MaskRequestBody and MaskResponseBody properties. The functions receive the captured request and response data as arguments (see callback arguments below) and should return the masked body as byte[], or null to mask the entire body. 
using Apitally;

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddApitally(options =>
{
    options.ClientId = "your-client-id";
    options.Env = "dev";
    options.RequestLogging.Enabled = true;
    options.RequestLogging.IncludeRequestHeaders = true;
    options.RequestLogging.IncludeRequestBody = true;
    options.RequestLogging.IncludeResponseBody = true;
    // Mask specific query parameters, headers and body fields
    options.RequestLogging.QueryParamMaskPatterns = ["^card_number$", "^account_id$"];
    options.RequestLogging.HeaderMaskPatterns = ["^X-Custom-Key$", "^X-Internal-"];
    options.RequestLogging.BodyFieldMaskPatterns = ["^credit_card$", "social_security"];
    // Mask request and response body using custom logic (see examples below)
    options.RequestLogging.MaskRequestBody = MaskRequestBody;
    options.RequestLogging.MaskResponseBody = MaskResponseBody;
});

var app = builder.Build();
app.UseApitally();
Callback function examples
using System.Text;
using System.Text.Json;
using Apitally.Models;

byte[]? MaskRequestBody(Request request)
{
    // Mask entire request body for admin endpoints
    if (request.Path?.StartsWith("/admin/") == true)
    {
        return null;
    }
    // Otherwise, return the original request body
    return request.Body;
}

byte[]? MaskResponseBody(Request request, Response response)
{
    // Mask entire response body for admin endpoints
    if (request.Path?.StartsWith("/admin/") == true)
    {
        return null;
    }
    // Mask specific fields in user profile responses
    if (request.Path?.StartsWith("/users/") == true && response.Body != null)
    {
        try
        {
            var json = Encoding.UTF8.GetString(response.Body);
            var data = JsonSerializer.Deserialize<Dictionary<string, object>>(json);
            if (data != null)
            {
                if (data.ContainsKey("email"))
                {
                    data["email"] = "******";
                }
                if (data.ContainsKey("phone"))
                {
                    data["phone"] = "******";
                }
                return Encoding.UTF8.GetBytes(JsonSerializer.Serialize(data));
            }
        }
        catch (JsonException)
        {
            // If parsing fails, return original body
        }
    }
    // Otherwise, return the original response body
    return response.Body;
}
Callbacks are applied before pattern-based field masking. The returned body is still masked using the default and custom BodyFieldMaskPatterns patterns.

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Exclude requests

You can exclude requests from logging using path patterns (regular expressions) via the PathExcludePatterns property. Like the masking patterns, these are case-insensitive and match anywhere within the request path. Use ^ and $ anchors for exact matches. Alternatively, you can provide a callback function with custom exclusion logic via the ShouldExclude property. The function receives the captured request and response data as arguments (see callback arguments below) and should return true to exclude the request from logging, or false to include it. 
using Apitally;

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddApitally(options =>
{
    options.ClientId = "your-client-id";
    options.Env = "dev";
    options.RequestLogging.Enabled = true;
    // Exclude paths matching certain patterns
    options.RequestLogging.PathExcludePatterns = ["/admin/", "/internal/"];
    // Exclude requests using custom logic (see example below)
    options.RequestLogging.ShouldExclude = ShouldExcludeRequest;
});

var app = builder.Build();
app.UseApitally();
Callback function example
using Apitally.Models;

bool ShouldExcludeRequest(Request request, Response response)
{
    // Exclude requests from a specific consumer
    if (request.Consumer == "internal-service")
    {
        return true;
    }
    // Exclude successful requests (only log failures)
    if (response.StatusCode < 400)
    {
        return true;
    }
    return false;
}
Excluded requests won’t be logged, but are still counted in metrics. To exclude endpoints from metrics, you can mark them as excluded in the dashboard.

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Callback arguments

The Request object passed to callback functions has the following properties:
PropertyDescriptionType
TimestampUnix timestamp of the request.double
MethodHTTP method of the request.string
PathPath of the matched endpoint, if applicable.string?
UrlFull URL of the request.string
HeadersArray of key-value pairs representing the request headers.Header[]
SizeSize of the request body in bytes.long?
ConsumerIdentifier of the consumer making the request.string?
BodyRaw request body.byte[]?
The Response object passed to MaskResponseBody and ShouldExclude has the following properties:
PropertyDescriptionType
StatusCodeHTTP status code of the response.int
ResponseTimeTime taken to respond to the request in seconds.double
HeadersArray of key-value pairs representing the response headers.Header[]
SizeSize of the response body in bytes.long?
BodyRaw response body.byte[]?