The Tool Desk
Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →To identify the process associated with a local port, run lsoff 8080, replacing 8080 with the port you want to inspect. lsoff is a command-line and text-interface tool for Windows, Linux, and macOS that lists processes associated with TCP and UDP ports. Its results can include process details, but permissions may leave fields such as the PID, executable path, or command line blank.
What lsoff shows
lsoff is designed for port-focused process lookup. You can search by port, process name, PID, command line, path, project, or service. The project documents an interactive text UI, tabular output when standard output is not a terminal, and JSON output for other tools or scripts. It says it gathers socket and process information directly rather than shelling out to lsof, ss, or netstat; those implementation details are project-reported, not independently verified.
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For example, lsoff 8080 searches for processes associated with port 8080. To search for a process name and request JSON, the README gives lsoff --json nginx. These are documented examples, not commands independently tested here. See the lsoff project README for current options and release information.
Do these 3 things before closing this tab:
1Fix the driver behind crashes, sound loss and screen glitches2Repair Windows errors before they cause bigger problems3Scan for outdated or missing drivers - takes under a minuteInstall lsoff on your operating system
The project documents support for Windows, Linux, and macOS, with several installation routes. Use the route that fits your system and package-management preferences.
#1 Best Overall
- VERSATILE USB TESTING: Test voltage from 3 to 20V DC and current from 0.05 to 3A (USB-A) and current from 0.05 to 5A (USB-C), covering most common standard USB ports, including Qualcomm Quick Charge ports
- EXTENSIVE MONITORING: Continuously monitor voltage, current, capacity/charge delivered, energy, and resistance (calculated) for up to 1000 hours, providing comprehensive data insights
- CONVENIENT DATA STORAGE: Store and recall up to 10 readings, allowing easy access to previous measurements for comparison and analysis
- OVERLOAD DETECTION: Detect voltage and current overload, ensuring the safety and protection of your devices and power sources during testing
- HIGH-RESOLUTION LCD: The hi-resolution LCD provides clear visibility of measurements, even in environments with low ambient lighting, ensuring easy reading of data
| Route | Documented command or guidance |
|---|---|
| Release binary | Download a binary for a supported target from the project’s GitHub releases. |
| WinGet | winget install yutat23.lsoff |
| Homebrew tap | brew tap yutat23/tap, then brew install lsoff. The README notes that Homebrew 6 may require a third-party tap trust step. |
| Go | go install github.com/yutat23/lsoff@latest |
| Build from source | Follow the project’s source-build instructions. The README says macOS builds require CGO because lsoff uses libproc. |
These are installation methods documented by the project, not independently tested installation results. The README also notes that the version is baked in at build time, so the output of lsoff -v may need to be checked against the source version after a rebuild or update.
Search for a TCP or UDP port
Look up a specific port
Run lsoff 8080 to search by port number. Replace the example with the port you need to investigate. The project documents a TUI for interactive use and tabular output when results are sent somewhere that is not a terminal.
Rank #2
- UPGRADED MULTIFUNCTIONAL USB C POWER METER: Detects the charging status and process of your USB-enabled or type c-enabled devices. Supports QC3.0, QC2.0 and BC1.2. A Must Gadget checks the charging performance (charging speed and quality) of the output wall/car/solar panel chargers and USB charging cables. It can be also used to find the highest current of the Wireless Charger, and test capacity and electric energy of power bank
- PROFESSIONAL SAFETY GUARD: Featured with over-voltage protection, over-current protection, under-voltage protection, low energy protection and alarm system. This upgraded USB Type C tester can detect safety and maximally protect the appliances from damaging. It will cut off output automatically and alarm by sound, while it will save data when power off suddenly
- MULTIPLE COLOR SCREEN DISPLAY MODES: New upgraded version offers 8 LCD main color screen display interfaces, allowing switching the display interface by pressing the key. With the new interface settings, this instrument can monitor voltage, current, capacity, electric quantity, power, load impedance, D+/D- voltage and other data of USB
- WIDE RANGE OF APPLICATION: Thanks to the PD protocol quick charging mode measurement technology, this new multimeter supports the updated iPhone X mobile phone. (Support iphone 8 / 8P / iPhone Xs quick charging, 29W power, 5V3A / 9V3A / 12V2.5A / 15V2A). It also can be applied to test other type C devices, Compatible With Galaxy S10/S9/Note 10 +, ChromeBookPixel, OnePlus and More
- QUALITY COMMITMENT: We always believe in the stability and continuous improvement of product quality. Package includes 1 x USB Tester. (Note: If the USB tester does not show any parameters, please insert the small adapter sent with the package into the side hole of the USB tester to trigger the PD charging function)
Search UDP sockets
Use lsoff -u 53 to search for UDP sockets associated with port 53, following the project’s example. UDP does not have TCP’s connection-state model or a TCP-style LISTEN state. lsoff describes its UDP results as sockets bound to a port with no remote peer, so treat them as bound UDP sockets rather than TCP listeners.
Quick wins for a faster PC:
Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Clear out junk files and repair common Windows errorsFree Scan →Scan for outdated or missing drivers - takes under a minuteDriver Scan →Filter by process information or get JSON
Search terms can target process name, PID, command line, executable path, project, or service, according to the README. Its example lsoff --json nginx requests JSON results for a process-name search. Consult the README for exact filter syntax and output fields if you are building a script around the output.
Rank #3
- 【7 Modes Display Monitor】 DROK USB Tester is equipped with digital color LED display screen, which can be switched between 7 display modes. This multimeter can be used to measure voltage, current, power, capacity. Through the 7 modes, you can clearly see the voltage, current, capacity and power during charging. Only 1 button to switch the display mode, simple and handy.
- 【Dual USB Output】 This item is equipped with USB-A USB-C input and dual USB 2.0 output. The output ports support PD QC 3.0 fast charge protocol. This meter can auto identify the fast charge protocol, which can charge your device among 3.6V to 12V 3A. Output Ⅰ can be used for device charging and data transfer, and output Ⅱ can only be used for charging.
- 【Multifunction】 DROK USB detector can be used for capacity checking, capacity clear, over voltage, under voltage, over current and short circuit alarm, which is easy to test the power, quality and know the health condition of your device chargers or USB cables.
- 【Easy to Use】 The multimeter only has Two button. Once you plug in the meter, you can test the parameter you want. The button Ⅱ can switch 7 modes display——VA(Voltage & Current), C(Capacity), P(Power), VA+C, VA+P, C+P, VA+C+P. 1. Please note that The latter 4 models is cyclic display. If you dislike the cyclic display modes, Just press the button Ⅱ to former 3 modes which are all fixed display. When voltage ≥ 5V, power on and long press button Ⅰ for 5 seconds to activate output.
- 【Application】 DROK USB Meter can be used for the devices between 3.2-30V and 0-5A. You can use this for 5V 9V 12V 24V 30V solar panel, power bank, battery charger, USB able.【Note】If you use USB-C IN and USB-A OUT, long press button I to Start Output.
Why process details may be missing
A port result does not guarantee that every process field will be visible. The project warns that permissions can prevent lsoff from retrieving the PID, executable path, or command line. If those details are essential, the README suggests running with root privileges on Linux or macOS, or as Administrator on Windows. Use elevated access only when appropriate for your system and task.
There are also platform-specific qualifications in the README. On Windows, command-line and current-working-directory collection uses NtQueryInformationProcess, which the project describes as an internal Microsoft API that could change. It also documents a limitation when a 32-bit lsoff process inspects command-line or working-directory details of a 64-bit process.
Rank #4
- 【USB Cable Performance Testing】Test USB cable continuity, functionality (charging, data transfer, high-speed signal), and measure internal resistance for power efficiency. Verify ground wire connection to outer shell for cable integrity, safety, and shielding.
- 【Type-C eMarker Chip Reading】Reads eMarker chip parameters in Type-C cables, providing detailed performance information (e.g., maximum current, voltage, data transfer rates) to help users fully understand cable capabilities and ensure safe, efficient device usage.
- 【High-Definition Color Display】 The USB cable checker features a 2.4-inch high-definition color display. With the left white button, you can easily switch between function pages to view real-time detailed status of the cable, including internal resistance, power delivery efficiency, and cable quality. This helps you quickly identify inferior cables.
- 【Wide Compatibility】The usb tester can accurately identify and verify USB cable versions, including USB 2.0 and USB 3.2. It integrates PD 3.0 and PD 3.1 protocol detection functions, enabling quick verification of whether the cable supports the latest PD 3.0/3.1 standards, ensuring the cable meets high-power charging and fast data transfer requirements.
- 【Multiple Power Supply Options】The black button on the left can flexibly switch the power supply mode, and support the use of AAA battery or Type C 5V to stably supply power to the USB tester
Use the kill option cautiously
lsoff documents -k as an action to terminate matching processes. For example, its README shows lsoff -k 8080 with confirmation and lsoff -k -y 8080 to skip confirmation; the project says the confirmation-bypass option is required when the command is piped. Verify the match before terminating anything: ending a process can interrupt the application or service using the port.
The project notes a remaining PID-reuse race on macOS: even after a recheck, the process could change in the final interval before the system’s kill(2) call. Do not treat the recheck as an absolute guarantee that the process being terminated is still the one originally identified.
Best Value
- 【Upgraded Multifuntional USB C Power Meter】The USB tester can detects Voltage, Current, Capacity, Electric Quantity, Power, Temperature, Resistance, Charging Time and other data of the USB or type C Port Devices. A Must Gadget checks the charging performance(charging speed and quality) of the output wall/car/solar panel chargers and USB charging cables. It can be also used to test capacity and electric energy of power bank. Measuring voltage: 3.6V-32V; measuring current: 0-8.0A.
- 【Latest Upgraded IPS Color Display Screen】New upgraded version offers 8 IPS main color screen display interfaces, allowing switching the display interface by pressing the key. The fonts are larger in one mode, which can read the data at a glance and facilitate viewing. This instrument can monitor Voltage, Current, Capacity, Electric Quantity, Power, Load Impedance, ect..
- 【Wide Range of Application】The USB power meter comes with A OTG adapter, supports PD3.0/PD2.0, QC3.0/QC2.0, BC1.2 and USB A or USB C port, supports the updated iPhone 13 Pro mobile phone. (Support iphone 13/12/11/X/iPhone Xs quick charging, 29W power, 5V3A/9V3A/12V2.5A/15V2A). Compatible with new MacBook Pro, MacBook, iMac, iMac Pro, Dell XPS, Acer Aspire, HP Spectre, Lenovo Thinkpad, Eluktronics, Razer Blade Stealth, Chromebook, Microsoft Surface Pro and more Type C devices and chargers.
- 【Test Power Bank Capacity】Before testing the power Bank,please fully charge the power bank,insert the usb voltage tester and double-click to clear the data,then connect the load or mobile phone (continuous discharge is required).ensure that the discharge voltage is 5V or 9V.(mAh is multiplied by 1.35 when discharge voltage 5V, and mAh is multiplied by 2.45 when discharge voltage is 9V, which is equal to the exact capacity of the battery of the power bank.)
- 【Professional Safety Guard】This USB C tester featured with over-voltage protection, over-current protection, under-voltage protection, low energy protection. This upgraded USB Type C tester can detect safety and maximally protect the appliances from damaging. It will cut off output automatically, while it will save data when power off suddenly.
When lsof may be a better fit
On Unix-like systems, lsof -i lists Internet socket files, with filters for protocol and port. It may suit you if you want broader open-file inspection or already prefer the lsof command-line workflow. lsoff is explicitly focused on ports and documents Windows, Linux, and macOS support; the cited lsof documentation describes a different scope and does not establish feature-for-feature parity.
For lsoff’s supported platforms and options, consult the project README. For lsof’s Internet-socket filtering, see the lsof documentation.
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