Shadow vs Strac — open-source Strac alternative for AI data protection

Strac is a commercial SaaS DLP platform: it discovers and remediates sensitive data in SaaS apps and, through a browser extension, can alert, block, redact or pseudonymise what employees send to ChatGPT and other AI tools. Shadow is an open-source (Apache-2.0) privacy layer for AI traffic that replaces sensitive values in API requests with realistic, reversible fakes and restores them in responses, streams and tool calls. Strac fits company-wide data governance across SaaS and browser use. Shadow fits developers, agents and services calling model APIs.

At a glance

	Shadow	Strac
Open source / licence	Yes, Apache-2.0	No, proprietary
Deployment	Endpoint HTTPS proxy, gateway (`/gw/<provider>/`), Rust library	SaaS platform plus browser extension
Protection method	Reversible realistic fakes from a persona; typed tokens for reports; optional redaction	Alert, block, redact, pseudonymise
Restores responses	Yes, automatically	Not documented
Streaming	Yes, SSE and NDJSON with split-fake reassembly	Not documented
Tool calls	Yes, arguments restored locally; intent-aware	No
Files	DOCX, XLSX, PPTX masked in place; PDF to text; CSV, JSON, HTML	Scans files in connected SaaS stores
Self-hosted	Yes, single binary, no account	No, SaaS
Price model	Free	Quote

What Strac does well

Coverage of web AI apps. A browser extension sees what employees type and paste into ChatGPT and similar web apps, which a network-level API proxy does not target.
More than AI. Strac connects to SaaS data stores for discovery and remediation, so one product can cover both data at rest and data flowing into AI tools.
Range of actions. Alert, block, redact or pseudonymise, chosen by policy.
Central management. Policies, alerts and reporting are managed from one console, which suits security teams overseeing many employees.

Where Shadow is different

Is Shadow a free alternative to Strac?

For AI API traffic, yes. Shadow is Apache-2.0, needs no account and sends no telemetry. It does not replace Strac’s SaaS discovery or browser-extension coverage.

Translate instead of block

Blocking a prompt stops the work, and people route around it. Plain redaction loses meaning. Shadow replaces jane@acme.com with hui.zhao@zhilan.cn, drawn from a persistent persona, keeps formats valid (Luhn, mod-97), and turns the fakes back into real values in the answer. Users don’t have to change how they work.

Built for APIs, agents and streams

Shadow restores server-sent event streams, including fakes split across events, and tool-call arguments before your tools run. That matters for coding assistants, agents and backend services, which browser extensions don’t see.

Intent-aware policy

Each request is classified as act, report, code or converse, and each value gets a fake, a typed token, a logged keep or a redaction. See intent-aware policy.

Office files in uploads

DOCX, XLSX and PPTX attached to API requests are masked in place and remain valid documents. See file masking.

What Shadow lacks

No central console, alerting, SIEM export, user coaching or SaaS data discovery. Configuration is a file per machine or container.

When should you choose Strac?

You need to govern employees’ use of AI web apps across a company.
You also want discovery and remediation in SaaS apps like Slack or Google Drive.
You want central policy, alerts and reporting for a security team.

When should you choose Shadow?

You want API and agent traffic masked without breaking answers.
You rely on streaming and tool calls.
You want a free, open-source, local tool with no third-party service in the data path.

Using them together

They cover different paths. Strac on managed browsers covers employees using AI web apps; Shadow on developer machines, CI runners and services covers SDKs, CLIs, IDE assistants and agents calling model APIs directly. Together, the web path and the API path are both covered.

How do they compare on accuracy?

Strac does not publish detection benchmarks that we found, and we could not test it without an account. Shadow’s benchmark publishes methodology and code.

Sources

Last reviewed: 2026-10-31. Strac is a trademark of its owner; this comparison is based on public documentation as of the review date.

Frequently asked questions

Is Shadow an alternative to Strac?

Partly. Strac is a SaaS DLP platform with a browser extension that can alert, block, redact or pseudonymise sensitive data in ChatGPT and SaaS apps. Shadow is an open-source privacy layer for AI API traffic that masks prompts with reversible realistic fakes and restores responses. Strac covers web apps and SaaS stores; Shadow covers API, agent and tool traffic on the machines where it runs.

Does Strac pseudonymise ChatGPT prompts reversibly?

Strac lists pseudonymisation among its actions. We could not verify from public docs whether live prompts are pseudonymised and restored in responses, so treat that as unverified. Shadow restores values in responses, streams and tool calls by default.

How much does Strac cost?

Strac is priced by quote; public pages we reviewed do not list prices. Shadow is free and open source under Apache-2.0.

Does Shadow cover ChatGPT in the browser?

No. Shadow intercepts AI API hosts such as api.openai.com in proxy mode. ChatGPT in the browser talks to chatgpt.com, which is not on that list, so what people type there is not masked. Shadow is designed for API traffic, not the consumer web chat UIs that browser-extension DLP tools target.

Can Strac scan SaaS apps like Slack or Google Drive?

Yes, Strac connects to SaaS data stores for discovery and remediation. Shadow does not scan data at rest; it only masks AI requests in flight.