Tree work is consistently one of the most dangerous occupations in the United States. We built a platform to close the gap between the safety standard that governs this work and the documentation that proves it's being followed.
Tree Safety Institute exists to make ANSI Z133-based safety documentation accessible to every tree service company, regardless of size. The standard that governs this work has been around since 1968 — the tools to document compliance with it have mostly been paper, clipboards, and hope.
When OSHA shows up — or when an incident happens — the question isn't whether your crew was trained. The question is whether you can prove it. We built the system that makes that proof automatic.
"The difference between a defensible record and an exposed liability is often a single piece of documentation."
Tree care has one of the highest fatality rates of any occupation in the U.S. The causes aren't random — they follow a documented pattern. Workers with less than one year of experience are involved in 23% of tree-worker fatalities. Companies with no documented safety plan account for the majority of fatal incidents.
OSHA references ANSI Z133 as the recognized industry standard for arboricultural operations. That means when a citation is issued, or when a case goes to litigation, your documentation — or its absence — is the record that matters.
We built Tree Safety Institute so that record exists automatically, is timestamped, is tied to specific Z133 clauses, and is verifiable by anyone who asks.
Source: ANSI Z133 safety research and industry fatality data.
ANSI Z133 is the American National Standard for Arboricultural Operations. First developed in 1968 at the request of arborists who wanted a codified safety framework, it has been updated by a committee of working arborists ever since. The 2017 edition — the one we build on — covers 10 sections across the full scope of tree care operations.
Most safety platforms teach "topics." Tree Safety Institute teaches clauses. When an employee completes a course on chainsaw use, their certificate references Z133 Section 6. When they complete aerial device training, it references Z133 Section 5. The documentation connects directly to the standard — which is exactly what OSHA wants to see.
We parsed all 454 clauses from Z133-2017 and mapped them into structured training modules. What that means in practice:
See how it works in practice
Explore the platformEvery course in Tree Safety Institute was built specifically for arboricultural operations. We don't adapt warehouse safety content or rename generic modules. Each program was developed from the ground up around the relevant standard.
The foundation. Covers every major hazard in tree care — climbing, aerial devices, PPE, rigging, electrical, chainsaw, chipping, and emergency procedures. Every worker, every role.
For arborists working near electrical transmission and distribution lines. Covers the specific qualification requirements, approach distances, and hazard controls that set line-clearance apart from general tree work.
Emergency response built for tree work — aerial rescue, chainsaw injuries, struck-by incidents. What your crew needs to know before something goes wrong.
Generic training platforms let you assign a "chainsaw safety" course and generate a completion certificate. That's useful. But when an OSHA inspector cites Z133 Section 6.2.1 in a violation notice, a generic certificate doesn't help your defense. A certificate that says Z133-6.2 — Chain Saw Use and Safety, completed March 2026 does.
We kept seeing the same problem: good crews doing the right things, but no way to prove it when it mattered. The paperwork was a mess, the records were on clipboards, and the standard that governed everything — Z133 — lived in a PDF that most field workers had never read.
We took Z133 apart clause by clause, built structured training around it, and added the compliance layer that turns completed training into defensible documentation.
The platform you're looking at today was built in close collaboration with people who run actual tree crews — and who know what it feels like when OSHA shows up and the records aren't ready.
Questions or feedback: hello@treesafety.org
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