Shadow vs Wald.ai — open-source, self-hosted Wald.ai alternative

Wald.ai is a commercial secure-AI service: it replaces sensitive values with context-aware substitutes before prompts reach ChatGPT, Claude or other models, keeps the substitutions consistent through a conversation, and restores them in the answer. Shadow does the same job as open-source (Apache-2.0) software you run yourself, as an endpoint proxy, gateway or Rust library, and adds streaming and tool-call restoration, an intent policy and Office file masking. Wald.ai suits teams that want a hosted chat product. Shadow suits teams that want the mapping and the traffic to stay on their own machines.

At a glance

	Shadow	Wald.ai
Open source / licence	Yes, Apache-2.0	No, proprietary
Deployment	Endpoint HTTPS proxy, gateway (`/gw/<provider>/`), Rust library	SaaS secure chat and API
Protection method	Reversible realistic fakes from a persona; typed tokens for reports; optional redaction	Contextual substitution with encrypted obfuscation maps
Restores responses	Yes, automatically	Yes
Streaming	Yes, SSE and NDJSON with split-fake reassembly	Not documented
Tool calls	Yes, arguments restored locally; intent-aware	Not documented
Files	DOCX, XLSX, PPTX masked in place; PDF to text; CSV, JSON, HTML	Not documented in the docs we reviewed
Self-hosted	Yes, single binary, no account	No, SaaS
Price model	Free	Per user (consumer plan about $19.99/month)

What Wald.ai does well

Substitution, not blocking. Wald.ai replaces values in context rather than refusing the prompt, so users keep getting useful answers.
Conversation consistency. It describes encrypted obfuscation maps that keep substitutions consistent across a conversation.
Ready-made product. A secure chat interface means non-technical users can start immediately, without configuring proxies or base URLs.
Contextual detection. Wald.ai positions its redaction as context-aware rather than purely pattern-based.

Where Shadow is different

Is Shadow a free, self-hosted alternative to Wald.ai?

Yes. Shadow is Apache-2.0, runs on macOS, Linux, Windows, servers and containers, and has no hosted component. The real-to-fake mapping lives in an encrypted vault on your machine. With a hosted service, prompts pass through the vendor before reaching the model; with Shadow, they are masked before they leave the machine.

Works with the tools you already use

Wald.ai is a destination: users chat in Wald’s interface or call its API. Shadow is in the path: set HTTPS_PROXY or a base URL and existing tools, IDE assistants, CLIs and SDKs that call a supported AI API keep working, now masked. Web chat such as chatgpt.com or claude.ai in a browser is not covered. See proxy mode and gateway mode.

Persistent persona

Shadow’s fakes come from a persistent persona, so consistency extends across conversations and days, not just one chat. Fakes keep their format: valid emails, Luhn-valid cards, mod-97 IBANs.

Streams, tools and intent

Shadow restores streamed responses and tool-call arguments, and its intent policy uses typed tokens for reports and handles provider-hosted tools explicitly.

Files

DOCX, XLSX and PPTX uploads are masked in place. See file masking.

What Shadow lacks

No chat UI, no hosted service, no admin console. Someone has to install and configure it.

When should you choose Wald.ai?

You want a ready-made secure chat for business users with no installation.
You prefer a managed service and per-user billing.
Your use is primarily English chat.

When should you choose Shadow?

You want data masked before it leaves your machines, with no third party in the path.
You want to keep using existing tools, SDKs and agents.
You use streaming, tool calls or Office uploads.
You need open-source code you can audit, at no cost.

Migrating from Wald.ai

Install Shadow on the machines or as a sidecar for the services that used Wald.ai’s API (quick start).
Point SDKs at http://127.0.0.1:8877/gw/<provider>/..., or set HTTPS_PROXY for whole-machine coverage.
Add your organisation names, customers and codenames as dictionary terms.
Test with shadow scan on typical prompts.
Give chat users an API-based AI client of your choice that goes through Shadow; the chatgpt.com and claude.ai websites are not masked.

How do they compare on accuracy?

Wald.ai does not publish detection benchmarks that we found. Shadow’s benchmark publishes methodology and code.

Sources

Last reviewed: 2026-10-31. Wald.ai 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 Wald.ai?

Yes, conceptually they are close. Both substitute sensitive values before a model sees them and restore them in the answer. Wald.ai is a cloud-hosted secure chat and API service; Shadow is a free, open-source layer that runs on your own machines as a proxy, gateway or Rust library.

How much does Wald.ai cost?

Wald.ai lists a consumer plan at about $19.99 per user per month; business pricing may differ. Check Wald.ai for current prices. Shadow is free and open source under Apache-2.0.

Is Wald.ai self-hosted?

Wald.ai is offered as SaaS. Public material we reviewed does not describe a self-hosted option. Shadow is self-hosted only, with no hosted component and no telemetry.

Which languages does Wald.ai support?

Wald.ai's API documentation states English only, with a 128K-token limit. Shadow's pattern detectors are language-independent for structured values, and its optional NER sidecar adds multilingual names via GLiNER; multilingual recall is measured on the benchmarks page.

Does Wald.ai work with agents and tool calls?

Public docs we reviewed do not describe tool-call or streaming restoration. Shadow restores both.