Visible pain is better than hidden friction, I'll grant you that. But suggesting devs will "learn the patterns" from groaning at config files is a bit optimistic. More often, they learn to add a `# nosemgrep` comment reflexively. That just replaces UI suppression with inline suppression, which is arguably messier and harder to audit later.
The real bottleneck you hinted at isn't about who does the triage, it's about who *pays attention* to it. A central team might get swamped, but at least the triage log is centralized. With dev-owned configs, you're relying on every developer to both understand *and* consistently apply the same logic. Good luck with that when you're trying to onboard someone new.
cg
Your point about the Semgrep config feeling more like writing code and speeding up adoption is key. That intuitive leap from code to rule was the single biggest factor for our team's acceptance. However, I'd add a caveat from a governance perspective: while developers learn those patterns quickly, you need a documented process for when a pattern becomes a team-wide rule.
For example, if one developer adds a `# nosemgrep` for a specific prop destructuring pattern, there should be a lightweight step to codify that exception. We use a simple rule in our repository's security folder; when a new safe pattern is identified, we submit a merge request to add a `pattern-not` to the shared rule. This prevents the same learning process from being repeated by every developer and stops the inline comments from proliferating beyond a few canonical examples. It turns individual learning into a team asset without reintroducing a central bottleneck.
RTFM — then ask for the audit
You're starting from a great place by focusing on your specific stack and the dev experience. The advice you're getting is solid, but for a small SaaS team, I'd lean toward Semgrep for one main reason: the learning curve you'd face with GitLab SAST is actually about learning Bandit's limitations, not about learning a tool.
Since you're using Flask, you'll quickly run into Bandit's generic Python rules flagging things that are perfectly safe in your framework context. You'll be stuck with those false positives unless you start writing Bandit plugin configs, which is more arcane than Semgrep's YAML.
The "slowing down devs" worry is real, but with Semgrep you can at least evolve the ruleset as your team learns. Start with the community `flask` security pack, then add a single rule together during a code review. That first rule you write to exclude your safe wrapper function will teach everyone more about your actual code patterns than a hundred generic alerts ever would 😄
Prod is the only environment that matters.
You're getting a lot of good perspectives on the tradeoffs, but as a fellow tinkerer who loves to automate, I have to chime in with something else. Everyone's right about the false positive tax, but they're missing a hidden time-saver in Semgrep for your specific stack.
When you write those few custom rules for Flask, you're actually creating reusable knowledge that plugs into a bunch of other workflows. For example, once you have a rule that identifies your safe database query pattern, you can use the same logic in your IDE extension for real-time hints. That means your devs are learning the secure patterns while they write code, not just getting blocked at the PR stage. It shifts the feedback loop from "slowdown" to "speed-up." That's the real win for a small, fast-moving team.
hugo
Oh I hadn't thought about the IDE integration angle. That's a good point. If the rules are *that* portable, it means the upfront config work could pay off way faster.
But does that IDE feedback work well for React JSX too? Or is it mostly a Python/backend thing? Asking because our stack is both.