
Notion
Logseq
Joplin
Evernote
Roam Research
Bear
Typora
A second brain, for you, forever. Obsidian is a powerful knowledge base that works on top of a local folder of plain text Markdown files.

Reblaze
Akto
Escape.tech
Salt
ZeroThreat.ai
Pynt.io
Metlo API Security
Open-source API security middleware — contract-first validation beyond the WAF.
Which is more popular?
Based on our record, Obsidian seems to be more popular. It has been mentioned 1533 times since March 2021.
Website, pricing, platforms and company facts side by side.
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| Website | obsidian.md | contractshield.dev |
| Pricing | ||
| Platforms | — | |
| Company | Startup from the United States | Startup from Switzerland · 1 - 9 employees · 2026 |
| Listed in |
In their own words, as submitted to SaaSHub.


No description of Obsidian yet.
ContractShield is open-source runtime API security middleware that validates every API request against your OpenAPI contract. It catches business logic attacks — authentication bypasses, BOLA/IDOR, parameter tampering, prototype pollution — that traditional WAFs and API gateways miss because they...
What each product offers, as listed by its team.


Possible disadvantages
An editorial look at what each product does well and who it suits.


Overall verdict
Why this product is good
Recommended for
Overall verdict
Why this product is good
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Walkthroughs and reviews on video.
OBSIDIAN: Getting Started, Facts & Pricing
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How often each product is chosen within a category, 0–100% relative to the other.


As answered by people managing Obsidian and ContractShield.dev.
ContractShield.dev's answer:
ContractShield is the only open-source middleware that enforces your OpenAPI contract at runtime — not just for documentation, but as a security policy.Most API security tools either scan for vulnerabilities (shift-left testing) or inspect payloads for known attack patterns (WAFs). ContractShield does neither. It sits inside your application and validates every request against what your API should do, not what attacks look like.
The result: it catches business logic attacks — authentication bypasses, BOLA/IDOR, parameter tampering, prototype pollution — that produce perfectly valid HTTP requests every WAF in the world allows through.
ContractShield.dev's answer:
vs. WAFs (Cloudflare, AWS WAF, Reblaze): WAFs can't see business logic. A GET /api/v1/users/456 from an attacker looks identical to a legitimate request. ContractShield understands the contract and blocks it.
vs. API security platforms (Salt, Noname, Traceable): These are enterprise-grade, agent-based, and expensive. ContractShield is lightweight middleware you install in 5 minutes with zero infrastructure changes.
vs. API testing tools (Akto, Escape.tech, Pynt): These find vulnerabilities before production. ContractShield blocks attacks in production — they're complementary, not competing.
Open source core (Apache 2.0): No vendor lock-in, fully auditable code, free for production use. Security certifications include OWASP ASVS Level 1, OpenSSF Scorecard, and SLSA Build Level 1 provenance.
Multi-platform from day one: Node.js, Python, and Java — covering ~80% of the API development market.
ContractShield.dev's answer:
Backend developers and API engineers building REST APIs who want runtime protection without adding infrastructure complexity
DevSecOps teams looking to enforce API contracts as security policy in CI/CD and production
CTOs and engineering leads at startups and mid-market companies who need API security beyond their WAF but can't justify six-figure enterprise platform contracts
Regulated industries (fintech, healthtech, identity verification) where API business logic protection is a compliance requirement
Teams already using OpenAPI specifications — ContractShield turns their existing documentation into an active security layer
ContractShield.dev's answer:
ContractShield was born from years of penetration testing. Running API security assessments for clients, we kept finding the same pattern: organizations had invested in WAFs, API gateways, and network security — yet their APIs were wide open to business logic attacks.
Authentication bypasses. BOLA/IDOR. Parameter tampering. Prototype pollution. Every single one produced clean, valid HTTP requests that sailed through every layer of infrastructure security. The vulnerability wasn't in the payload — it was in the logic.
We realized the gap: infrastructure tools protect the transport layer, but nobody was protecting the contract layer — the actual business rules that define what an API should and shouldn't do.
So we built ContractShield as middleware that reads your OpenAPI specification and enforces it at runtime. Your API contract becomes your security policy. If it's not in the spec, it's blocked. If auth is required, it's enforced. If the schema says no, it means no.
We open-sourced the core under Apache 2.0 because API security shouldn't be a luxury reserved for enterprises with six-figure budgets. We continue to offer Penetration Testing as a Service (PTaaS) alongside the product — because automated protection and expert assessment together provide the strongest security posture.
ContractShield.dev's answer:
ContractShield.dev's answer:
ContractShield PTaaS (our own penetration testing platform runs on ContractShield). Privacy is our moto, contact us for more information.
Share your experience with using Obsidian and ContractShield.dev. For example, how are they different and which one is better?
External articles and on-site reviews we used to compare the two products.


One thing to note: Notion bills itself as an Evernote competitor for personal users. It can be—but it's too much for most people, and its offline functionality isn't the best. If you love the idea of Notion, go right...
This app is the kind of thing that, if you’re into it, will have you exploring its various ins, outs, and add-ons for days and weeks on end. Obsidian uses the Markdown format for its notes (which means they can be...
However, it's important to note that Obsidian's whiteboard functionality is not as robust as dedicated collaboration tools. While it lacks real-time basic collaboration features, Obsidian compensates with its vibrant...
We have no reviews of ContractShield.dev yet. Be the first one to post
Recommendations tracked on public social media and blogs since March 2021.


After publishing my first plugin which really helped me dive into Obsidian, I realized that the tool I'm using for note taking is missing a very simple, but handy feature - templates for base-based notes. - Source: dev.to / about 15 hours ago
The reasons live somewhere else: in practice notes in an Obsidian vault, one note per convention, with the repos it has held in. A note starts as an idea, moves to trialing, and only becomes enforced once I've applied it again in a few... - Source: dev.to / 4 days ago
It's the team version of the second brain you build with Obsidian and Claude. - Source: dev.to / 8 days ago
Tracking ContractShield.dev since Feb 2026.
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