Alternatives

Other tools in this space, and when they might suit you better.

Écluse is one answer to a problem many people are working on, and nowhere near the only good one. Its core idea, holding fresh packages behind a delay and applying a policy at a chokepoint, has been reached independently by a range of projects and vendors, several more mature than Écluse is today.

This page is a genuine, good-faith guide. Each entry says what a tool offers and when to reach for it; if one fits you better than Écluse, use it. For why Écluse exists and how it differs, see MOTIVATION.md.

Self-hosted filtering proxies

A service you run and point your clients at, which filters or gates packages on the way through. The closest cousins to Écluse.

• Verdaccio: a lightweight, widely-adopted self-hosted npm registry that proxies and caches upstreams. It supports multiple uplinks with ordered fallback, and since v6.4 ships a bundled package filter: a minimum-age gate (minAgeDays), version blocklists, per-package allow exceptions, and replacement of a blocked version with an older one. That filter is first-party now, not only a third-party plugin, making Verdaccio a genuine open-source npm repository-firewall configuration for an npm-only team. Reach for it when you want to run your own npm registry and a metadata age gate is enough. Écluse differs in that it merges versions across upstreams semantically rather than falling back in order; drives denials from OSV advisories with an immediate remediation fast lane, so a fix ships the moment it lands; swaps the advisory index atomically; and mirrors on demand into a registry you already run instead of caching into its own storage. Verdaccio's filter is also metadata-only and npm-only.

Package-manager and bot cooldowns

Per-project, per-consumer controls that need no infrastructure: right when you can guarantee consistent configuration across everyone who installs.

• npm's minimum-release-age cooldown, pnpm's minimumReleaseAge, and equivalents in bun and uv: an install-time delay set in the project or per consumer; newer package-manager releases are moving toward stronger install-time defaults. Reach for it for immediate, zero-infrastructure protection of a project you control.
• Renovate and Dependabot cooldowns: delay update proposals until a version has aged. Reach for it when updates already flow through a bot and you want a cooldown with no new moving parts.
• SafeDep PMG (Package Manager Guard): an open-source local guard that wraps your package-manager commands (a shell shim or CI step), enforcing cooldowns alongside threat-intelligence checks and OS-level sandboxing across the npm and Python families, and explicitly protecting AI coding agents. Reach for it for per-developer and per-agent defence-in-depth with no central service to run.

Commercial platforms and hosted services

Turnkey, vendor-supported central enforcement without building or maintaining it yourself.

• JFrog Artifactory with Curation: a full artifact platform whose curation layer enforces policy at the proxy, including age-based ("immature package") gating and malicious-package blocking, which JFrog describes informally as a firewall for open-source packages. Reach for it for one vendor-supported platform across many ecosystems, with enterprise support.
• Sonatype Nexus Repository with Repository Firewall: quarantines suspicious components at the proxy using behavioural and metadata signals, releasing safe ones automatically. Reach for it for mature behavioural detection backed by a large intelligence database and a widely-deployed repository manager.
• Harness Dependency Firewall: a commercial, centrally-managed control that blocks risky open-source dependencies at the proxy. Reach for it for central enforcement inside the Harness platform.
• StepSecurity Secure Registry: an authenticated proxy you point CI, developers, and artifact managers at, enforcing cooldowns and malicious-package blocking. Reach for it for a managed central chokepoint you don't operate yourself.
• Cloudsmith: a hosted, multi-format registry with a policy engine that can quarantine or deny by version, metadata, and other criteria. Reach for it for a managed registry with policy controls when you'd rather not self-host.
• Socket: behavioural analysis of packages (install scripts, network access, and more), surfaced in CI and pull requests. Socket also offers Registry Firewall, a registry-protocol proxy that applies metadata filtering across roughly eight ecosystems. Reach for it for deep per-package behavioural signals plus a proxy-level filter.
• pkgwarden: a hosted, commercial curated registry that quarantines new versions for 14 days and filters on CVE data, across npm and PyPI. Reach for it for a managed curated registry with a fixed quarantine and CVE filtering.
• Managed cloud registries, AWS CodeArtifact and Google Artifact Registry, give you a chokepoint, storage, authentication, and dependency-confusion controls, but no freshness policy of their own, so pair them with a cooldown above. Reach for it as the backing store you likely already run; Écluse delegates storage to exactly these rather than replacing them.

Complementary tools (not substitutes)

These address a different part of the problem and pair with any of the above.

• Provenance and attestations: npm provenance (Sigstore / SLSA) and npm audit signatures attest where and how a package was built. Use alongside a cooldown for cryptographic build-origin verification.
• Malicious-package scanners: e.g. GuardDog and SafeDep vet, heuristics that flag malicious packages. Use alongside a delay to add detection a delay alone won't provide.

Where Écluse fits

Écluse aims at one corner of these trade-offs: an enforced, central chokepoint that's open and self-hostable, composes in front of the managed registry you already run rather than replacing it or hosting packages itself, and applies a deny-by-default freshness policy consistently, so a malicious-package disclosure is answered by comparing timelines rather than auditing logs. npm is the first supported ecosystem; the core is registry-agnostic, with PyPI and RubyGems on the roadmap. It's also early and unproven (see MOTIVATION.md → What Écluse is not).

If a different point on these trade-offs serves you better, use one of the tools above.