The bugs that tests miss but users find
Missing null checks, undefined access, and optional chaining gaps that crash at runtime
Async timing bugs, state mutations during render, and concurrent access issues
Boundary conditions, empty arrays, zero values, and special inputs that break in production
Incorrect conditionals, off-by-one errors, and business logic that doesn't match intent
See how Bug Hunter spots issues before they reach production
function getUserName(user) {
// Crashes if user is null/undefined
return user.profile.name.toUpperCase()
}No null checks — crashes on undefined user
function getUserName(user) {
return user?.profile?.name?.toUpperCase() ?? 'Unknown'
}Use optional chaining with fallback
async function loadData() {
setLoading(true)
const data = await fetchData()
// Component might be unmounted!
setData(data)
setLoading(false)
}State update after unmount causes memory leak
async function loadData() {
let cancelled = false
setLoading(true)
const data = await fetchData()
if (!cancelled) {
setData(data)
setLoading(false)
}
return () => { cancelled = true }
}Track mounted state with cleanup
// Process all items except last
for (let i = 0; i < items.length - 1; i++) {
process(items[i])
}
// Bug: skips last item unintentionallyOff-by-one: skips the last item
// Process all items
for (let i = 0; i < items.length; i++) {
process(items[i])
}
// Or use forEach for clarity
items.forEach(item => process(item))Use correct boundary or forEach
Bug Hunter thinks like a QA engineer with infinite patience. It traces every code path, considers every edge case, and asks "what if?" at every branch.
Traces all possible execution paths through your code
Tests boundary conditions, empty values, and unusual inputs
Imagines real-world usage patterns that could trigger bugs
Parse Code Flow
Builds a mental model of how data flows through your code
Identify Risk Points
Finds places where things can go wrong
Trace Edge Cases
Simulates unusual inputs and boundary conditions
Report with Context
Explains the bug scenario and how to fix it
Would this bug wake you up? Bug Hunter catches them first.
Null pointers, undefined access, and type errors that only appear with real data
Race conditions that work 99% of the time — until they don't
Logic errors that silently corrupt data until someone notices
Tests check what you expect.
Bug Hunter checks what you forgot.
Let Bug Hunter catch the issues that would wake you up. Free for 14 days, no credit card required.