Peter Parker uses small electronic "Spider-Tracers" of his own design that allows him to track objects or individuals. Typically, Spider-Man plants one on a departing enemy, or throws one to adhere to an escaping enemy, and then follows the target to their hideout for a later attack. Spider-Man sometimes also uses a launching device in his web-shooters for better range and accuracy.
A tracer's outer casing is shaped like a spider, with legs for aerodynamic flight. The tracers are small enough to remain unnoticed, in general, but sometimes a target finds a tracer and destroys it
Spider-Man uses a small electronic receiver to follow the signals of his tracers, but eventually, he modifies the tracers to emit a signal he can follow with his spider-sense so that he will be able to know whether or not he is in the proximity of the tracer. According to what he once said to Hank Pym (who noted that Peter may actually be smarter than him if he was able to design this at fifteen when Pym spent years developing similar technology for his helmet) , he is able to sense the tracer within a 100-yard radius. The receiver, however, offers better range. Spider-Man is unable to sense a tracer that had been taken out of Manhattan at one point. The receiver, however, allows him to follow it to the town of Scarsdale, New York, some 20 miles (32 km) away. It is not yet established if the changes to his spider-sense documented in "The Other" storyline have affected Spider-Man's ability to sense the tracers. 
Besides Spider-Man, Daredevil can pick up the signal with his radar sense from the Spider-Tracers due to his heightened sense of hearing being able to hear the signal. Unlike Spider-Man, it is more difficult for Daredevil to follow the signal, as he must drown out all other sounds around him to maintain focus. 
His enemies have used the tracers to lure him into a trap. Enemies with sufficient technical knowledge can reprogram the tracers into overloading his spider-sense, making it hard for him to tell the difference between real danger and the tracer. Or they just attune it to his sixth sense and they can simply put on a target of their own, just like Tracer did in "The Other".
His clone, Ben Reilly, can also pick up the signal from Peter's tracers. Ben also developed a modified version of the original tracer into a simpler 'Micro-Dot' form. Like Peter's, these devices can be fired from Ben's web-shooters and can adhere to most surfaces. They fly like miniature Frisbee. May Parker's spider-sense operates on a different frequency than her father's, requiring her to use the tracer device, as Peter's tracers do not trigger her spider sense.
Following her rescue from an obsessed kidnapper, Mary Jane Watson wears an amplified version of a spider-tracer in a necklace pendant. It carries a boosted signal so Spider-Man can follow it over a longer distance.
Revenge Of The Spider-Slayer
The Spider-Tracers become useless since Spider-Man can no longer pick up their signal due to the loss of his spider-sense. However, in the "Road to Spider-Island" storyline, from working with Horizon Labs, Spider-Man made new and improved spider-tracers with listening devices, G.P.S., and camouflage. Some further modifications include using them as weapons with one example of combating Hydro-Man by freezing him solid with a cryogenic Spider-Tracer. This particular advancement is then applied toward a medical transplant delivery system.
When Doc Ock tried to use the Octavius Lens as a way to convince the world that he could save them, Spider-Man intercepted an International Meeting between the World Leaders and was able to identify that Chameleon was posing as Al Gore. When Doc Ock requested Chameleon to be unhanded, Spider-Man placed a Spider-Tracer on his back to track where he was going.
However, Doc Ock was able to discover the Spider-Tracer and gave the Chameleon and different set of coordinates. Spider-Man, along with the Avengers were able to track Chameleon's location. This lead to a confrontation between the Avengers and the Sinister Six.
Using his resources at Parker Industries, Peter Parker built an improved version of the Spider-Tracer. He made it available for commercial use, having the option of being linked to a Webware. The new spider-tracer featured a two-year battery life, was water-proof and was super durable.
Using it during a mission against the terrorist group known as Zodiac, Spider-Man along with The Prowler utilized the spider-tracer as a means of retrieving his personal Webware, which contained data not available to the public.
House of M
Ultimate Spider-Man Animated Series (Earth-12041)
Michael Tan was a disgruntled employee at Stark Industries who was fired after Tony Stark rejected his technopathic devices. Michael swore he would get his revenge on Stark, and activated his latest creation, which seemingly vaporized him. Unknown to Stark and Spider-Man (who was at Stark Industries after teaming up with Iron Man to defeat Juggernaut), Michael's molecules had been dispersed, and his consciousness found a new host in one of Spider-Man's Spider-Tracers.
During a second battle with the Juggernaut, the Spider-Tracers begin to rapidly multiply, and Michael made a fluid-like collection of Spider-Tracers his new body. Michael, now calling himself "Swarm" attacked Spider-Man and Iron Man, destroying the Hall of Armor in the process. Swarm was only defeated after the two heroes flew through the villain's "mouth" and Spider-Man neutralized the Spider-Tracers.
Marvel Cinematic Universe
In Earth-199999, the Spider-Tracer is designed by Tony Stark, that is incorporated into Spider-Man's Web-Shooters. The device is automated and emits a signal that allows Spider-Man to track its location through the use of his Web-Shooters.
- The original Spider-Tracers cost twenty bucks to create. Parker Industries's version cost $16.23 to manufacture.
- They are sold for $49.99.
- 287 Appearances of Spider-Tracer
- 11 Minor Appearances of Spider-Tracer
- 15 Media Spider-Tracer was Mentioned in
- 4 Images featuring Spider-Tracer
- Item Gallery: Spider-Tracer