Feature Flags

All optional capabilities in kumo are behind feature flags, so you only compile what you need.

Reference Table

Flag	Pulls in	Purpose
(default)	—	CSS + regex selectors, all file stores, all middleware, HTTP cache, link extractor
`derive`	`kumo-derive`	`#[derive(Extract)]` for zero-boilerplate CSS extraction
`jsonpath`	`jsonpath-rust`	JSONPath selector on `Response`
`xpath`	`sxd-xpath`	XPath selector on `Response`
`browser`	`chromiumoxide`	Headless Chromium fetcher for JS-rendered pages
`stealth`	`wreq`, `wreq-util`	TLS/HTTP2 fingerprint spoofing + browser stealth patches¹
`claude`	`rig-core`	`AnthropicClient` for LLM extraction
`openai`	`rig-core`	`OpenAiClient` for LLM extraction
`gemini`	`rig-core`	`GeminiClient` for LLM extraction
`ollama`	`rig-core`	`OllamaClient` for local LLM extraction
`llm`	`rig-core`, `schemars`	Base LLM traits (implied by all provider flags)
`postgres`	`sqlx`	`PostgresStore`
`sqlite`	`sqlx`	`SqliteStore`
`mysql`	`sqlx`	`MySqlStore`
`cloud`	`object_store`	`CloudStore` — backend-agnostic cloud storage (LocalFileSystem + InMemory included)
`cloud-s3`	`object_store/aws`	Adds Amazon S3 backend support to `CloudStore`
`cloud-gcs`	`object_store/gcp`	Adds Google Cloud Storage backend support to `CloudStore`
`cloud-azure`	`object_store/azure`	Adds Azure Blob Storage backend support to `CloudStore`
`persistence`	—	`FileFrontier` — file-backed URL frontier that survives restarts
`redis-frontier`	`redis`	`RedisFrontier` — distributed URL frontier via Redis
`otel`	`opentelemetry`, `opentelemetry_sdk`, `opentelemetry-otlp`, `tracing-opentelemetry`	OTLP/gRPC export of all spans and events

¹ The stealth feature compiles BoringSSL from source. It requires cmake and nasm on the build machine. See Stealth Mode for setup instructions.

stealth is experimental because it depends on native BoringSSL builds and upstream browser fingerprint libraries can change quickly. For release work, verify the published wreq and wreq-util license metadata before tagging.

Common Combinations

Data science / scripting

kumo = { version = "0.2", features = ["sqlite", "derive"] }

Production crawl

kumo = { version = "0.2", features = ["postgres", "redis-frontier", "otel"] }

Cloud storage

# Write to S3
kumo = { version = "0.2", features = ["cloud-s3"] }

# Write to GCS
kumo = { version = "0.2", features = ["cloud-gcs"] }

# Write to Azure Blob
kumo = { version = "0.2", features = ["cloud-azure"] }

LLM extraction

# Cloud provider
kumo = { version = "0.2", features = ["claude"] }

# Local model
kumo = { version = "0.2", features = ["ollama"] }

Full-stack

kumo = { version = "0.2", features = [
    "derive", "xpath", "jsonpath",
    "browser", "stealth",
    "claude",
    "postgres", "redis-frontier",
    "cloud-s3",
    "otel",
] }