TL;DR: cside vs otto-js
- otto-js monitors client-side scripts through a JavaScript-agent architecture, observing behavior after scripts load. A predictable agent from a known origin can be identified and fed a clean script.
- cside downloads every script to its own infrastructure for server-side analysis, in real time, from 100% of real user sessions with no sampling. Because cside is embedded in real traffic, it cannot be selectively evaded the way a scheduled agent can. Every payload archived for forensics.
- Want a JS-agent monitor: otto-js. Want full session coverage, server-side payload analysis, and forensic-grade QSA evidence at a lower total cost: cside.
What is otto-js?
otto-js, formerly DEVCON, is a client-side JavaScript security platform focused on PCI DSS v4 compliance and malvertising protection. It monitors first-, third-, and Nth-party script behaviour at runtime and markets a one-line integration to automate PCI DSS 6.4.3 and 11.6.1 evidence, alongside SOC 2 and third-party-risk reporting. It targets SMB and mid-market e-commerce teams that need a fast, affordable PCI solution without a dedicated application-security team, and it integrates with GitHub Advanced Security and common e-commerce platforms.
Credit where it's due: otto-js publishes its pricing openly (starting around $30/month), which is rare in this space, and it is genuinely a like-for-like client-side tool rather than a checkbox feature bolted onto a larger platform. We don't think price is the right axis to compete on here.
How otto-js works
otto-js deploys a client-side JavaScript agent that observes and analyses scripts as they load and execute in the visitor's browser, surfaces them in a dashboard for review, and offers features marketed as real-time mitigation. It generates Content Security Policy and access-control configurations and integrates runtime vulnerability scanning through GitHub Advanced Security.
The honest open question, and the one we'd encourage any buyer to put to both vendors, is about depth and coverage: how complete is each tool's view of what a script actually does across real user sessions, and what can it show you afterwards? That is the question that separates a compliance dashboard from a security tool.
How cside goes further
otto-js is built to satisfy PCI DSS 6.4.3 and 11.6.1. cside is built to stop client-side attacks, with compliance as a by-product of real security.
cside monitors every script executing in the real browser and performs AI-driven analysis on the script's actual content, not just a list of which scripts are present. That catches novel and evolving threats, including targeted attacks that only activate under specific conditions such as certain geographies, time windows, or device types.
For forensics, cside keeps immutable archives of every script payload with full version history. When an auditor or an incident-response team asks what happened, you have the actual code and a complete timeline, not a behavioural change log.
cside also goes beyond client-side script security with a dedicated fingerprinting product: device fingerprinting, bot detection, and AI agent detection, so you can cover both client-side security and visitor identity from one vendor. And cside publishes a public status page at status.cside.com, a public trust portal at trust.cside.com, and a QSA-validated PCI dashboard, so you can verify our claims for yourself.
Try cside before you buy. cside has a free plan, so you can sign up, deploy, and explore the platform yourself, with no sales calls or procurement process. And our support team is one message away whenever you need a hand.
Sign up or book a demo to get started.
Related resources
Founder and CEO of cside. Previously a product manager on Cloudflare Page Shield (now Cloudflare Client-Side Security). Co-chair of the W3C Anti-Fraud Community Group and a Forbes 30 Under 30 honoree. Building accessible security against client-side attacks, web security is not an enterprise-only problem.
