Harmonic Security vs Nightfall AI

Harmonic Security sells software that shows security teams how employees and AI agents use generative AI tools and stops sensitive data from going into them. It was founded in 2023 (its About page dates the founding to August 2023) by CEO Alastair Paterson, the former chief executive of Digital Shadows, and CTO Bryan Woolgar-O'Neil. It launched in October 2023, jointly headquartered in London and San Francisco, and its privacy policy names Harmonic Security Limited in London and Harmonic Security Inc. in San Francisco. It says it has raised $76 million in total: a $7 million seed round led by Ten Eleven Ventures (October 2023), a $17.5 million Series A led by Next47 (October 2024) and a $50 million Series B led by Crosspoint Capital Partners, announced on October 14, 2026, when it reported more than 100 customers and more than 90 staff in the US and UK. We found no acquisition. The platform is sold as three packages. Explore uses a browser extension to find the AI tools in use and gives prompt-level visibility, usage intelligence, sensitive data detection and risk scores for each app; Harmonic says it covers more than 1,000 AI applications, including AI features inside SaaS tools. Guide adds an endpoint agent for desktop AI apps, IDEs and command-line tools such as Claude Code and Codex, inline coaching (block, warn or log), granular policies and webhook alerts for SIEM and SOAR tools. Command adds MCP client and server discovery, permissions on what agents may read, write and execute, and data protection inside agentic workflows; prompt injection detection is listed as coming soon. Its locally installed MCP Gateway, launched in October 2025, intercepts MCP traffic on Windows, macOS and Linux. Instead of pattern matching, Harmonic classifies prompts with its own small language models, which it says decide in under 200 milliseconds. **AI compliance coverage** Harmonic treats compliance as a by-product of governance. Its compliance page says it flags high-risk uses such as automated hiring screens and credit scoring "so you can apply the specific guardrails the EU AI Act and local laws require", keeps an audit trail of AI interactions, and blocks health and personal data from unapproved AI tools for HIPAA and GDPR. Documentation mapping its controls to specific regulations is available on request, as is EU hosting. For Harmonic itself, its trust center lists SOC 2 Type 2 and ISO/IEC 27001:2022, with a SOC 2 report available on request, and its site footer shows SOC 2 Type 2 and ISO 27001 badges. ISO/IEC 42001 and the NIST AI RMF also appear in the trust center's list, but the site shows no badge or certification claim for either. **Who it's for** Security and IT teams that want to let staff use ChatGPT, Claude, Copilot, Cursor and similar tools while keeping company data out of them. Harmonic has industry pages for technology, legal, insurance and healthcare, and its site quotes customers at Apax and Advisor360.

Nightfall AI is a data loss prevention (DLP) platform that finds sensitive data in SaaS apps, email, endpoints, browsers and AI tools and stops it from leaking. It was founded in 2018 by Isaac Madan and Rohan Sathe, came out of stealth in November 2019 (it originally launched as Watchtower AI) and is based in San Francisco; its privacy policy names the operating company as Shoreline Labs, Inc. Sathe is now chief executive. Nightfall has disclosed $60.3 million in funding: $20.3 million at its 2019 launch, with the latest round co-led by Bain Capital Ventures and Venrock, and a $40 million Series B led by WestBridge Capital in August 2022. We found no later round and no acquisition. The product has five parts. Data Detection and Response scans SaaS apps through their APIs, including Slack, Google Drive, Gmail, Jira, Confluence, Salesforce, Microsoft 365, Notion and Zendesk. Data Exfiltration Prevention uses lightweight agents and browser plugins on macOS and Windows (Chrome, Firefox, Safari and Edge) to stop browser uploads, AI prompts, personal cloud sync, USB transfers and pushes to personal code repositories, and traces files from corporate origin to external destination. AI Security covers employee AI use (personal ChatGPT accounts, unmanaged copilots and browser AI tools) and AI agents, with hooks for Cursor, Claude Code and VS Code, MCP server discovery, and monitoring of Claude Enterprise through Anthropic's Compliance API. Data Discovery and Classification is an add-on that scans data at rest, and Nyx, launched in July 2025, is an AI agent that investigates incidents and tunes policies. In September 2026 Nightfall opened early access to an MCP Gateway that enforces policy on agent tool calls before they run. **AI compliance coverage** Nightfall's compliance material is about data protection frameworks, not AI regulation. Its help center explains how it helps with HIPAA, PCI DSS, SOC 2 and ISO 27001, and its detectors cover PII, PHI, payment card data, secrets and source code, with an out-of-the-box PCI detection template. We found no material on the EU AI Act, ISO 42001 or the NIST AI RMF. Its security page says Nightfall is SOC 2 Type 2 certified and that its databases are all in the United States. **Who it's for** Security teams that want one tool for SaaS DLP, endpoint exfiltration and employee and agent use of AI, particularly companies with sensitive data in Slack, Google Workspace and Microsoft 365. Its published customer stories include a health tech company using it to keep Slack and GitHub HIPAA compliant.