Privacy-First Writing: Why Client-Side Linting Matters

Every time you paste text into a cloud-based grammar checker, you're making a privacy trade-off. Your unreleased product documentation, confidential API guides, proprietary content strategy, and private drafts upload to third-party servers for processing. Even with privacy policies and encryption in transit, your content passes through infrastructure you don't control.

For technical writers, documentation teams, and anyone handling sensitive content, this trade-off is increasingly unacceptable. Client-side linting offers a better approach: professional-grade writing quality checks that run entirely on your device, with zero data transmission.

The cloud-based grammar checker privacy problem

Popular writing tools like Grammarly, ProWritingAid, and similar services process your content on remote servers. This architecture creates several privacy concerns:

Your content leaves your device

When you type into a cloud-based grammar checker or paste content for review, the text transmits to company servers for processing. Natural language processing is computationally expensive, so these tools perform analysis in the cloud, not locally.

This means:

• Drafts of unreleased features pass through third-party infrastructure before your product launches
• Confidential business strategy documents are processed by servers you don't administer
• API documentation with security implications exists on systems outside your security perimeter
• Personal writing is accessible to the service provider, subject to their data retention and access policies

Privacy policies provide limited protection

Service providers offer privacy policies promising not to sell your data or use it for advertising. These policies are legally binding, but they don't eliminate risk:

Policy changes: Terms of service can change. A company acquired by a new owner might revise privacy commitments.

Legal obligations: Government subpoenas, court orders, and legal discovery can compel companies to provide access to stored content.

Security breaches: Even with strong security, cloud services face constant attack. A successful breach exposes whatever content the service stores.

Employee access: Administrators, support staff, and engineers at the service provider potentially have technical access to stored data, even if policies prohibit use.

Business models evolve: Free or low-cost services might later introduce revenue models that rely on data analysis, training AI models on customer content, or other uses not originally disclosed.

Compliance and regulatory concerns

Organizations in regulated industries face additional constraints:

GDPR requirements: European privacy law restricts how personal data can be processed and stored, especially by third-party services outside EU jurisdiction.

HIPAA compliance: Healthcare organizations cannot use tools that process protected health information (PHI) without Business Associate Agreements and specific safeguards.

Financial regulations: Banking and financial services have strict requirements about data residency, access controls, and third-party processing.

Government and defense contracts: Public sector work often prohibits uploading content to commercial cloud services without specific authorization.

Corporate security policies: Many companies ban using external services to process confidential content, even with non-disclosure agreements in place.

If your organization has compliance requirements, cloud-based grammar checkers may violate policy by default.

The "trust us" model isn't enough

Cloud-based writing tools ask users to trust that:

• Content won't be accessed by unauthorized parties
• Data retention policies are followed strictly
• Security practices remain robust indefinitely
• Business models won't change to monetize stored content
• Breaches won't occur despite constant attacks

This trust model might be acceptable for casual blog posts or public content. It's inadequate for sensitive documentation, confidential drafts, or content subject to regulatory requirements.

What client-side linting means

Client-side linting processes your content entirely on your local device—in your browser or on your computer—without sending text to remote servers. This architectural difference fundamentally changes the privacy model:

Processing happens locally

When you use client-side linting, the linting engine runs on your device:

WebAssembly in the browser: Modern browsers support WebAssembly (WASM), allowing compiled programs to run at near-native speed directly in the browser. Vale can be compiled to WASM and executed entirely client-side.

No server contact for linting: After the initial load of the linting engine and rule packages (one-time downloads that cache locally), all processing happens on your device. Your content never transmits to external servers.

Results generate locally: Issue detection, style checking, and suggestions compute on your device and display without any network communication.

Zero data transmission

Client-side architecture means:

Your drafts stay on your device: Text you paste, type, or upload never leaves your browser or computer. The linting engine processes content locally and displays results without external communication.

No content stored on external servers: Since processing is local, there are no remote databases storing your documents, no cloud archives of your drafts, and no server-side logs of what you've written.

Offline functionality: After initial setup, client-side linting works without internet connectivity. Cache the linting engine and rule packages, then lint completely offline—proof that no data transmission is occurring.

Privacy by architecture, not policy

The key distinction: client-side linting makes privacy violations technically impossible, not just policy-prohibited.

Cloud-based tools: Promise not to misuse your data (policy-based privacy) Client-side tools: Cannot access your data because it never leaves your device (architecture-based privacy)

Architecture-based privacy is objectively stronger. You don't need to trust privacy policies, hope security remains robust, or worry about future business model changes. The tool literally cannot access your content because it never receives it.

How ProseLint Web implements client-side linting

ProseLint Web demonstrates practical client-side linting using modern web technologies:

WebAssembly execution

Vale, the prose linting engine, compiles to WebAssembly and runs entirely in your browser. When you visit ProseLint Web editor:

1. WASM binary loads once: Vale's WebAssembly build (about 6.2MB compressed with Brotli) downloads and caches in your browser's Cache API and IndexedDB
2. Rule packages download on demand: Style guides (Microsoft, Google, Red Hat, etc.) download as needed and cache locally
3. All subsequent operations are local: Linting, issue detection, and quick-fix suggestions compute in your browser without server contact

Browser storage for persistence

ProseLint Web uses client-side storage technologies for state and caching:

IndexedDB: Stores downloaded rule packages, user preferences, and editor state. This is browser-local storage—data stays on your device, not synced to cloud services.

Cache API: Holds the Vale WASM binary and static assets for fast loading and offline access.

No cloud synchronization: Your content and settings don't sync across devices because there's no cloud storage. This is a feature, not a limitation—each device keeps its own local data.

Network activity is minimal and auditable

You can verify ProseLint Web's privacy claims using browser developer tools:

Open DevTools Network tab: Watch network activity while linting. You'll see:

• Initial loads: Vale WASM binary, rule package ZIPs (one-time, cached)
• Linting activity: Zero network requests—all local processing

Audit with browser extensions: Use privacy-focused browser extensions to monitor outbound requests. ProseLint Web makes no requests to external servers during linting.

Verify offline: After initial package downloads, disable your network connection and continue linting. Everything works offline, proving local processing.

This transparency allows technical users to verify privacy claims rather than trusting them.

Practical privacy benefits for different users

Different users gain distinct privacy advantages from client-side linting:

Technical writers and documentation teams

Documentation often covers unreleased features, confidential roadmaps, and proprietary APIs:

Pre-release content stays private: Draft documentation for features not yet announced remains on your device, not uploaded to third-party services where leaks could occur.

API security details don't leave your network: Documentation describing authentication mechanisms, security configurations, or system architecture stays within your organization's security perimeter.

Competitive information protected: Content describing product differentiators, unique approaches, or strategic positioning doesn't pass through external services where employees of competitors might work.

Enterprise and compliance-focused organizations

Regulated industries and security-conscious companies benefit significantly:

GDPR and privacy law compliance: Client-side processing means personal data never crosses borders or enters third-party systems, simplifying compliance.

Security policy adherence: If organizational policy prohibits uploading content to external services, client-side tools comply by default.

Audit trail simplification: No need to track which external services processed what content, when, and under which agreements—content never left your infrastructure.

No Business Associate Agreements needed: Healthcare organizations don't need BAAs with writing tool vendors because no PHI is transmitted.

Open-source maintainers and contributors

Open-source documentation has different privacy needs:

Pre-release documentation: Draft docs for upcoming releases can be checked before public announcement without risk of premature disclosure.

Security-sensitive content: Documentation describing security fixes, vulnerability details, or security-critical configurations stays private until coordinated disclosure.

Personal privacy: Contributors using personal devices to write docs don't expose their writing patterns, topics of interest, or contribution history to commercial services.

Journalists, researchers, and writers handling sensitive topics

Investigative journalism and research often involve sensitive content:

Source protection: Draft articles describing confidential sources or sensitive information stay on the writer's device.

Research data privacy: Academic and scientific writing containing unpublished research, participant data, or proprietary findings remains private.

Censorship resistance: Writers in jurisdictions with content restrictions can check writing quality without exposing topics or angles to external services that might be monitored or compelled to disclose access.

Comparing privacy models: cloud vs. client-side

Let's examine concrete privacy scenarios:

Scenario 1: Unreleased product documentation

Cloud-based tool: You paste API documentation for an unreleased feature. Content uploads to the grammar service's servers. Even with NDA-protected privacy policies, the content exists outside your organization's security boundary. If the service experiences a breach or receives a legal subpoena, your content could be exposed.

Client-side tool: You paste the same documentation. Content processes in your browser without transmission. The API documentation never leaves your device. Breach or subpoena of the linting service yields nothing because your content was never transmitted or stored externally.

Privacy advantage: Client-side prevents your content from existing in external systems where it might be accessed.

Scenario 2: Healthcare documentation with PHI

Cloud-based tool: Writing patient care guides or medical documentation that references protected health information. Uploading to a cloud grammar checker potentially violates HIPAA unless you have a Business Associate Agreement and the service meets all regulatory requirements.

Client-side tool: PHI-containing content processes locally. No transmission means no HIPAA concerns from the linting tool itself (you still need to secure your local device, but that's your existing responsibility).

Privacy advantage: Client-side eliminates the need to vet external service providers for healthcare data handling.

Scenario 3: Confidential business strategy

Cloud-based tool: Drafting internal communications about layoffs, acquisitions, or strategic pivots. Content upload creates external copies subject to the service provider's retention policies, employee access, and security practices.

Client-side tool: Confidential content processes locally and never enters external systems. No external copies exist to be retained, accessed by service employees, or exposed in breaches.

Privacy advantage: Client-side ensures confidential content remains genuinely confidential—not just "protected by policy" but architecturally isolated.

Scenario 4: Government and defense contracting

Cloud-based tool: Working on documentation for government systems or defense contracts. Security requirements often prohibit using commercial cloud services for content processing without specific authorization and security validations.

Client-side tool: Local processing means content doesn't enter commercial cloud infrastructure. Tool usage complies with restrictions on external data processing.

Privacy advantage: Client-side tools can be used without violating contractual restrictions on data handling.

Privacy doesn't require sacrificing quality

The common assumption: privacy-focused tools must compromise on features or quality. Client-side linting disproves this:

Professional rule packages: Vale's style guides from Microsoft, Google, Red Hat, GitLab, and Elastic are industry-proven. Client-side execution doesn't limit access to professional quality rules.

Advanced format support: Client-side linting handles markdown, MDX, AsciiDoc, HTML, and other formats—often better than cloud-based tools optimized for general prose.

Real-time feedback: WebAssembly performance means client-side linting is fast enough for real-time feedback as you type (in editor integrations) or near-instant results on demand (in browser tools).

Customization and control: Client-side tools can offer full customization (like Vale's extensible rule system) without concern that custom rules expose proprietary style preferences to service providers.

Privacy and quality aren't opposites. Architecture choices that prioritize privacy can deliver quality equal to or exceeding cloud-based alternatives.

Future-proofing your privacy

Client-side linting protects against future privacy risks that are hard to anticipate:

AI training concerns: Cloud services increasingly use customer data to train AI models. Even if current privacy policies prohibit this, future policy changes might allow it. Client-side tools eliminate this risk—content that was never transmitted can't be used for training.

Acquisition and ownership changes: A writing tool company acquired by a larger organization might face pressure to change data practices, integrate with other services, or monetize data in new ways. Client-side architecture makes your past content immune to future policy changes because the service never possessed it.

Data breach evolution: Attack techniques evolve. A service with strong security today might face breaches tomorrow using techniques not yet known. Content that was never stored externally is immune to future breaches.

Regulatory expansion: Privacy regulations are expanding globally. Client-side tools that never transmit data automatically comply with current and future privacy laws because data never crosses boundaries or enters third-party systems.

Getting started with privacy-first linting

Transitioning to client-side linting is straightforward:

For individual writers

1. Visit ProseLint Web editor for browser-based client-side linting
2. Select a style guide matching your content needs
3. Paste or upload content and lint locally
4. Verify privacy: Open browser DevTools, watch the Network tab during linting, and confirm zero requests to external servers

For organizations

1. Evaluate privacy requirements: Identify which content cannot be uploaded to external services
2. Adopt client-side tools like ProseLint Web for sensitive content workflows
3. Update security policies: Approve client-side linting tools for use with confidential content
4. Train teams: Educate writers on the privacy advantages of client-side processing

For open-source projects

1. Link browser-based linting in CONTRIBUTING.md for contributors
2. Explain privacy benefits: Note that contributors can check style without uploading content to commercial services
3. Maintain Vale CLI in CI: Use Vale CLI for enforcement while providing browser option for convenience

Conclusion: privacy is a fundamental right, not a premium feature

Writing quality tools shouldn't require compromising content privacy. Your drafts, confidential documentation, and sensitive content deserve protection—not just through privacy policies that might change, but through architecture that makes privacy violations technically impossible.

Client-side linting delivers this. By processing content entirely on your device, tools like ProseLint Web provide professional-grade writing quality checks without data transmission, external storage, or trust requirements. Your content stays yours—private by default, secure by design.

Try ProseLint Web for your next sensitive document and experience privacy-first linting that doesn't compromise on quality.

Resources

• ProseLint Web editor — client-side linting with zero data transmission
• Vale CLI — open-source prose linter for local and CI use
• GDPR compliance information — understanding European privacy law
• OWASP Privacy Risks — privacy threat modeling