What "offline" actually means
A genuinely offline SAST tool makes zero outbound network connections during the scan itself: no source code upload, no telemetry ping, no analytics beacon, no "phone home" for a license check mid-scan. Rule evaluation, AST parsing, taint analysis, and report generation all happen against your local filesystem, using a rule set already present on disk. The only network-adjacent step, if any, is license activation — and even that can be designed to validate against a signed key offline rather than calling out to a vendor server.
Cloud SAST vs offline SAST
| Cloud SAST | Offline SAST | |
|---|---|---|
| Source code leaves your machine | Yes, uploaded for analysis | Never |
| Internet required to scan | Yes | No |
| Telemetry / usage tracking | Usually, varies by vendor | None, if genuinely offline |
| Air-gapped environments | Not supported | Supported |
| Infrastructure to deploy | None — SaaS | None — standalone binary |
| Data residency / sovereignty risk | Depends on vendor's hosting region | Not applicable — data never transmitted |
Not every offline-capable tool is offline by default — check whether telemetry or update checks are opt-out rather than absent.
Why it matters
For most SaaS products, uploading code to a vendor's cloud is an acceptable trade-off for convenience. For a specific set of sectors it is not a trade-off at all — it is a compliance or contractual non-starter: defense contractors and classified environments, banks and financial institutions under regulatory data-residency rules, healthcare organizations bound by HIPAA or equivalent, government agencies, and law firms bound by attorney-client privilege and confidentiality obligations to clients whose code they may be auditing. For these, the question is not "is this vendor's cloud secure" — it is "are we contractually or legally allowed to transmit this code at all."
How to verify any tool's "offline" claim yourself
Don't take a vendor's marketing copy at face value — a claim you can't verify is not evidence. The standard way to check whether a program makes any outbound network connection is to capture traffic on the machine while it runs, using a packet capture tool most operating systems already have:
$ sudo tcpdump -i any 'host not 127.0.0.1 and host not ::1' &
$ ./the-sast-tool scan ./my-project
# ... scan runs ...
# if tcpdump printed zero lines during the scan, zero packets left the machine.This excludes loopback traffic (127.0.0.1 / ::1, which never leaves the machine anyway) and shows only packets addressed to an external host. Run it once during a scan with network access available — if the tool is genuinely offline, this will report nothing for the duration of the scan.
What this looks like for StaticCodeAudit specifically
This exact protocol, plus a pre-written DPO-facing clause you can cite verbatim in a data processing agreement, plus a public dogfooding report — StaticCodeAudit is scanned against itself on every commit, and the report is published — all live on the security page.
Read the full offline verification protocol →Frequently asked questions
Does "offline" mean the tool never needs internet, ever?
No — it means the analysis itself (parsing, rule evaluation, report generation) never requires or uses a network connection. Downloading the binary in the first place, or receiving a new rule pack update, are separate, occasional, explicit actions — not something that happens silently during a scan.
Is offline SAST inherently more secure than cloud SAST?
It removes an entire category of risk — code interception in transit, storage on a third party's infrastructure, exposure through that vendor's own breach — but it does not automatically make the tool's detection quality better or worse. Detection accuracy and offline operation are separate properties; evaluate both independently. See real detection benchmarks alongside any offline claim.
Can license validation happen without a network call?
Yes — by validating a cryptographically signed license key against a public key baked into the binary, rather than calling out to a licensing server. This is a deliberate design choice, not automatic; check specifically whether license activation is offline too, not just the scan itself.
How do I verify a tool is offline if I can't run tcpdump (e.g., on a locked-down machine)?
A network-level firewall rule blocking all outbound traffic for the scan process, then confirming the scan still completes successfully, achieves the same proof without needing packet capture tools installed. Any approach that observably blocks or logs outbound connections works — the point is independent verification, not any one specific tool.
Why does this matter even outside regulated industries?
Even without a compliance mandate, source code is intellectual property. Sending it to a third party's cloud — however reputable — means trusting that vendor's security posture, breach history, and data retention practices with something the company may not want to trust anyone with. Offline operation removes that trust requirement entirely rather than asking you to accept it.
See the verification protocol in full
The tcpdump command, the DPO clause, and the public dogfooding report all live on one page.
Read the security page Open the live demo report