Top Pick: Best Hammock Straps
Kammok Python Hammock Strap
Kammock’s Python 10 feet long straps came out on top in terms of usability, durability, versatility, and tree-friendliness.
Each strap boasts 20 connection points, enabling users to achieve tight, knot-free hangs make them easy to use in a variety of settings. What’s more, the wide, flat polyester webbing is easy to wind. When you are finished with the straps, you can stuff them into the Diamond Shell stuff sack. The straps also come in a 15 feet version, so you should never find yourself without a long enough strap system.
Kammock’s Patented Nanoweave polyester can withstand plenty of repeated use and exposure to the elements. It won’t rip, tear, or fade under pressure. Even the polyurethane and silicone stuff sack is designed to handle a beating. It’s DWR coating makes it 100% waterproof.
Each Python strap can hold as much as 500 pounds. As a result, these straps are perfect for a couple that’s looking to hang together. The loop system connection points are also incredibly durable. They can be used with virtually any hammock that uses carabiners.
The webbing’s variable width, which ranges from 0.75 to 1.5 inches, displaces some of the pressure you’d typically put on trees. As a result, these hammock straps will help you reduce your footprint while preserving the wonders of the natural world.
The Bottom Line: As our best overall pick, the Kammok Python 10 suspension straps are versatile, tree-safe, and trustworthy.
Choosing the best hammock Straps for a Perfect Hang
Whether you’re looking to catch some Z’s or score some fresh air, there’s no better place to do it than a hammock. Of course, it’s almost impossible to relax when you’re hanging from precarious suspension straps. Making things worse, inferior ropes and straps are likely to damage the trees. If you want to score an uninterrupted night of sleep, you are going to need a reliable pair of hammock straps. We’re here to set you in the right direction!
To help you out, we’ve brought you an all-encompassing guide to buying hammock straps. Also, you’ll find our unbiased review of seven of the hammock straps on the market. Finally, we offer our honest thoughts on the overall winner deserving of the title “Best Hammock Strap”.
How to Choose Hammock Straps
Why Do You Need Straps?
We often get asked whether hammock straps are essential. Ultimately, they keep you suspended in your hammock while maintaining the integrity of your support trees. The leave-no-trace quality of these technical systems makes them a far better choice than a cord or rope. Since they do not require you to memorize intricate knots, they’re also the least time-consuming and most user-friendly hammock hanging options.
Selecting the Strap System for your Hammock
Daisy Chain Straps
Daisy chain webbing makes for a virtually hardware- and knot-free suspension system. These versatile strap pairings are typically made from polyester webbing. They consist of a base strap with a series of evenly spaces loops that are sewn to it. These loops serve as open-ended connection points. Users can anchor the daisy chain webbing to anchor points and then select the connection points that provide them with the best hang height and tension. Overall, this is a fuss-free system that is suitable for beginners.
Whoopie Sling Suspensions
Whoopie slings are adjustable rope apparatuses. They make excellent hammock suspenders. Whoopie slings consist of four parts, which include an adjustable loop, a bury, a tail, and a fixed eye. The adjustable loop attaches to a strap. Meanwhile, the fixed eye connects to the carabiner attached to the hammock straps.
The bury is a woven fabric sleeve that goes over a length of thin cord or rope. The bottom of this cord is called the tail. When you tug on a whoopie sling’s tail, the entire apparatus tightens. You can also loosen a whoopie sling by pulling this cord toward the anchor points. However, once you put weight on your hammock, the sling automatically locks. These suspension straps offer unmatched versatility while also presenting a minimal learning curve.
Buckle suspensions consist of webbing and cinch buckles. The webbing is wrapped around anchor points before being fed through a cinch buckle. The cinch buckle consists of a metal buckle, a metal bar, and a continuous loop.
You can tighten your buckle suspension by tugging on the end of the webbing. This type o system is highly reliable and slip-resistant.
Once upon a time, knot-based suspenders were the primary system used in the hanging of hammocks. Knot-based suspension straps consist of two skillfully tied pieces of cord or rope.
Suspension knots allows users to adjust the tension of their hammock. However, it takes time and effort to master this time-honored craft.
Factors to Consider When Picking the Best Hammock Straps
Weight-bearing straps that are constantly wrapped around trees and exposed to the elements must be exceptionally durable. The dominant material choice is polyester webbing. Unlike nylon webbing, polyester webbing does not easily succumb to mildew and mold. Since it is also less abrasive than nylon webbing, it is the more LNT-friendly webbing choice.
Maximum Supported Weight
Always check the maximum supported weight of your suspension straps.The material’s tensile strength often determines this number. Tensile strength is the amount of weight that 1 square inch of fabric can bear without breaking.
Make sure that the weight limit aligns with that of your anchor (if applicable) and hammock. The median weight limit for hammock straps is 400 pounds. However, we’ve come across straps that offer as little as 300 pounds and as much as 2,000 pounds.
Strap Length and Thickness
If you’re constantly anchoring your hammock between different tree sets, you’re going to need a set of adjustable tree straps. In most cases, you’ll want your straps to be between 6 and 10 feet long. They need to be long enough to cover the distance between the hammock and trees and wrap around the tree.
The straps should also be at least 1 inch in width and with tapered ends. Broader straps do a better job of redistributing weight. As such, they are less likely to damage trees.
In an ideal world, you can carry your hammock and suspension straps with you when your camping and hiking. Straps should coil easily so that they fit into a small carrying sack.
Ease of Setup
A well-hung hammock should be 5-feet off the ground, slack, yet not droopy. You should be able to slap your suspension straps up in a matter of minutes or seconds. The system should come down as quickly as it went up.
Connection points, anchors, loops, and hardware should all be easy to decipher. There’s no need for technicalities.
Fit for Use with Trees
When you’re looking at hammock straps, you see a lot of hype surrounding leave-no-trace and LNT-friendly products. Wide, flat polyester, and nylon webbings are far less damaging than tubular cords and ropes. After all, these products roll along the surface area of a tree, creating a detrimental level of friction.
How do I Hang a Hammock with Tree Straps?
First, you’ll need to find two trees that are at least 10 feet apart and roughly 1 foot in diameter. Place your hammock straps against the trees, making sure it is at least 5 feet from the ground. Pull the straps around the circumference of the tree. If you’re working with a daisy chain or basic tree strap, pull one end of the strap through the appropriate connection loop.
Attach the end of this strap to a whoopie sling and/or a carabiner. Connect the carabiner to your hammock strap. Repeat the same process on the opposite sit. Voila! You have a weight-bearing nest that is fit for slumber. Cautiously enter your hammock to test its tension – just in case you end up on the ground.
Can’t I just use a rope to hang my hammock?
You can use a rope to hang a hammock. That said, most people find modern suspension straps to be far easier and more reliable. A rope is not always the most LNT-friendly suspension straps. Moreover, it can be a pain in the neck to untangle, untie, and coil lengthy cuts of material.
Looking for other Hammock Accessories?
- Stay protected from mother nature with a great rainfly for hammocks and the best hammock bug net.
- Ensure you have a top notch sleep system for your hammock with our reviews of the best sleeping bag for hammock camping, the best underquilt, and the best sleeping pad for hammock camping.
- If you can’t find any trees, then consider purchasing a portable hammock stand.
Kammok Python 10 Hammock Straps
Best Hammock Straps
- FAST AND EASY KNOTLESS SETUP: Install your hammock in seconds without complicated knots. Simple anchoring mechanism makes setup a breeze even for a first timer! Compatible with all hammocks featuring carabiner or toggle suspension systems.
- LIGHTER AND STRONGER: A lightweight alternative to traditional heavy and bulky straps. Our patented Nanoweave construction eliminates extra stitching and bulk, dramatically decreasing weight while maintaining the same durability and improving portability. Hang from the hammock straps safely up to 500 lb.
- THE PERFECT HANG EVERY TIME: Each strap is 10 ft long with 20 points of connection (20 ft of length/40 points of connection combined) to adjust for your comfiest hang. The high-tenacity polyester webbing ensures a no-stretch hang, keeping you off the ground and elevated. High visibility reflective tracers make it easier than ever to navigate in the dark.
- LIFETIME WARRANTY & GREAT CUSTOMER SERVICE: We stand by the quality of our gear. Every Kammok product is covered by a lifetime warranty, so you can be confident your gear will outlast your adventures.
- MAKE A DIFFERENCE: Every Kammok product purchased goes towards supporting youth leadership & character development through Explore Austin and social and environmental causes through 1% For the Planet. Kammok is a certified B Corporation.
As the best all-around hammock straps, the 10 feet long Kammock Python Straps boast impressive specs for a wallet-friendly price. The 40-point, 20-foot daisy chain strap system offers unmatched durability, ease of use, and versatility. What’s more, the LNT-friendly design elements make for virtually footprint-free installations.
First off, these straps are made from ultra-durable 40D polyester webbing. This high-tensity material offers excellent abrasion resistance and overall strength. You can repeatedly run these straps over rough patches of bark without risking damage. On top of that, the intricate webbing weave eliminates any potential for stretching.
Python’s streamline design and complimentary storage sack make it a preeminent option for backpackers and travelers. After all, these straps weigh just over 8 ounces. Yet, they have the strength to offer a collective 1,000-pound weight capacity.
The 20-loop daisy chain makes for easy and flexible installations. The knot-free system makes for quick and painless setups and teardowns.
Kammock has outdone themselves with this risk-free hammock support system. They’ve even backed this incredible product with a lifetime warranty. As such, shoppers don’t have to take a leap of faith when investing in this incredibly versatile piece of outdoor gear.
- Length: 10 feet
- Width: .075 to 1.5 inches (variable)
- Material: Polyester webbing with Sil/PU coated stuff sack
- Weight Limit: 500 pounds
- Covered by a lifetime warranty
- No stretch
- Features high-visibility reflectors
- 1000 lb weight limit
- Does not come with carabiners
Bottom Line: Two reliable 12-inch anchor points and a pair of Kammock Pythons are the only things you need to guarantee yourself a stress-free hammock-based slumber.
ENO Helios Hammock Suspension Straps
Best Straps for Ease of Adjustment
- HAMMOCKING DONE RIGHT: Pairs perfectly with any ENO Hammock (not included). Features an easy-to-adjust bury splice tension system that helps prevent slippage. Let the napping begin
- ADVENTURE IN STYLE: The Helios Hammock Suspension System weighs only 4.1 ounces and is made from super-strong Dyneema line with a polyester blend tree sling. Designed to support up to 300 lbs.
- MASTER THE ART OF LOUNGING: Measuring over 8 feet, allowing you to wrap them around big trees or wherever your adventure (nap) takes you.
- TAKE ON THE GO: Includes a Sil Nylon Compression Stuff Sack that compacts the straps down to the backpack friendly size of 3" x 4."
- PLEASE NOTE: ENO attempts to reduce potential waste by using every bit of fabric available in production, so the color of the stuff sack and stitching might vary from what is pictured.
It’s not easy to alter the position of tension of a hammock after it has been hung. However, the ENO Helios Suspension Straps take the hassle out of alterations. The Helios Hammock-Hanging System is a glorified whoopie sling. The proprietary Microtune adjustment system enables you to set and adjust the position of your hammock without tying a single knot or undoing any connection points making them super easy to use.
Each strap and bury sling combo measures approximately 8 feet in length. The straps are made from ultra-durable Silverlite Cord and 1000D poly filament webbing. So long as you stay under the system’s 300-pound weight limit, you can trust the Helios straps to provide you with unwavering overnight support.
ENO is a partner of the Leave No Trace initiative. The 1-inch poly filament webbing won’t slip or chafe tree bark. As such, you can rest easy knowing you are not making a negative impact on your natural surroundings.
What’s more, the set weighs a mere 4.3 ounces and comes with a drawstring storage bag. For this reason, we highly recommend this tree-safe hammock strap set for nature-loving backpackers.
- Length: 8 feet 1 inch
- Width: 1 inch
- Material: Silverlite™ Cord / 1000D and Polyfilament Webbing
- Weight Capacity: 300 pounds
- Straps are made from Silverlite Cord
- Proprietary Microtune adjustment system
- Easy to use knot-free setup
- Weighs just 4.1 ounces
- Low weight limit
Bottom Line: If you’re trekking into camp on foot, you’ll want a set of these lightweight ENO whoopie slings in your gear pack.
TENTSILE No Trace Tree Tent Kit
Best LNT Suspension System
- PROTECT THE TREES: We want to protect every tree species around the World! The No Trace Kit means you don’t have to worry about damaging the delicate bark on some species, so you can safely pitch your Tentsile on any strong, healthy anchor tree.
- TREE WRAPS: Soft and fuzzy fabric wraps, with velcro patches you can cut to shapes to secure each in place. The kit includes a pack of 3, each measuring: Length: 6 foot 6-inches / 2 meters, width: 6-inches weight: 1 pound / 0.4kg
- TREE PROTECTOR STRAPS: Loops at both ends to attach a carabiner. The kit includes a pack of 3, each measuring: Length: 6 foot 6-inches / 2meters , width: 3-inches / 7.5cm, weight capacity: 5 tons, weight: 2-pounds / 0.9kg
- STEEL QUICKLINKS: With Screw gate for locking shut. Suitable for all conditions. The kit includes a pack of 3, each with a weight capacity (major axis) of 40kN (kilonewton). The pack weighs 1.11 pounds.
- NO TRACE GEAR BAG: The total kit comes in a No Trace Gear Bag that is made from recycled tent fabric. The kit weighs a total of 4.4 pounds or 1.9 Kg.
The TENTSILE No Trace Tree Tent Kit is designed to support TENTSILE’s proprietary tree tents and giant hammocks. This incredible strap network comes with three weight-bearing straps, three protective tree wraps, and three durable steel carabiners.
As indicated by its name, the Tentsile No Trace Tree Tent Kit is the ultimate hammock suspender for tree-hugging hikers. Despite having a weight capacity of 5 tons, this system is designed to prevent trees from incurring damage. The soft, velcro-lined wraps are designed to eliminate friction between the tree protector straps and tree bark. You’d be hard-pressed to find a more arbor-centric hammock strap manufacturer.
The thing about the Tentsile hammock straps is they are designed to support triangular pods. As such, we’d only pair them with Tentsile’s tree tents. Since these models are a bit intricate, they’re not the best options for beginner hammock hangers. After all, locating a trio of suitable posts or trees takes a good amount of skill and determination.
Overall, we were impressed with how easy it was to install and level the tree wraps and tree protector straps. We felt confident that the carabiner stop gates would keep everything in place for extended periods. If you’re looking to fade into the backdrop of the forest without harming the flora and fauna, check out Tentsile’s pod hammocks.
- Length: Includes three 6 1/2-foot straps and wraps
- Width: 3 inches
- Material: Steel, Velcro, recycled tent fabric,
- Weight Capacity: 2 tons
- Straps come with a No Trace gear bag made from recycled tent fabric
- Screw gate locks shut for slip-free hang sessions
- Kit weighs just 4.4 pounds
- Can also be used to support tree tents
- The three-strap system is only compatible with TENTSILE’s giant hammocks
Bottom Line: At just over 4 pounds, this kit isn’t the lightest suspension system on the market. Still, this suspension system enables you to camp under the stars without leaving a trace.
ENO Atlas Hammock Suspension System
Best Beginners Option
- NEW FEATURES: Atlas XL Straps just got even better; Tapered construction reduces weight and increases tree protection; Reflective stitching for better nighttime visibility; Smaller storage bag
- EASY SETUP: Each strap is 13' 6" long and features 20 attachment points, making them ideal for thicker trees; Suspends hammocks between trees 10' to 14' apart; Simple setup doesn't require knots
- MADE TO LAST: Durable 1000D Polyfilament webbing is lightweight and strong; Supports up to 400 lbs.
- INCLUDES: One set of Atlas straps (two straps total) with compact storage sack (3.5" x 7"); Hammock and carabiners sold separately
- ENO GIVES BACK: As a proud partner of Leave No Trace we support their efforts toward teaching responsible enjoyment of our wild places
Atlas’s Suspension System is the perfect hammock strap set for beginners. These 9-foot daisy chains let you hang your hammock without tying a single knot. The thoughtful addition of reflective stitching makes for frustration-free installations in low-light conditions. With 30 optional attachment points to choose from, you’ll have no trouble finding suitable anchors for your hammock.
When you’re new to hanging hammocks, it can be difficult to tell if you’re damaging the trees. Atlas’s tapered webbing disperses hammock weight in a way that minimizes tree injuries. The extra-wide poly filament webbing won’t dig into tree bark.
Most hammock newbies look to avoid risks and injuries. Since these straps offer a secure setup and 400-pound weight limit, you can cast your nighttime worries away. Pair these reliable suspension straps with your favorite carabiner-equipped hammock, and you’re good to go.
- Length: Two 9-foot straps
- Width: .75-1.5 inches (variable)
- Material: 1000D Polyfilament Webbing
- Weight Capacity: 400 pounds
- Won’t mark up tree bark
- Easy to Use, easy to clean
- 30 connection points for various tree settings
- Leave-no-trace shelter gear
- Only comes in one color
Foxelli Hammock Straps XL
Best Hammock Straps for Couples
- FAST + EASY SETUP: It takes less than 1 minute to set up a hammock with Foxelli Camping Hammock Straps, with no complicated knots needed. Our two XL Hammock Straps provide safe suspension between any anchor points up to over 20 feet apart. They are tree friendly, and can also safely attach to posts, large rocks, roof racks, boat masts, docks and more. Our hammock tree straps are 100% compatible to use with any tree hammock.
- EXTRA LONG + ADJUSTABLE: Includes two hammocking straps that are 20 feet long combined and have 40 hammock attachment loops + 2 tree attachment loops in total, allowing you to adjust the height of your hammock and achieve the perfect hanging angle. Straps’ extra length increases your options for finding the ideal location to place your hammock.
- SAFE & RELIABLE: Always feel secure with Foxelli outdoor hammock straps. Each strap holds up to 1000 LBS (2000 LBS total). They are constructed with high density, 100% no-stretch, heavy duty, triple stitched polyester webbing, which ensures that you’ll stay at the same height at all times, with no worries about falling to the ground. Straps are designed for many years of use, with no signs of fraying.
- LIGHTWEIGHT & PORTABLE: The hammock tree hanging straps set includes 2 hammock straps and easily fits into the included small carrying bag. Entire set is ultralight and weighs only 0.66 LBS, making it excellent for backpacking, hiking, camping and travel. It’s a must have for your camping gear. Note: carabiners are not included.
- RISK-FREE PURCHASE: Don’t worry about missing Amazon’s 30-day return window. If for any reason, you are not 100% happy with your hammock straps, let us know and we will give you your MONEY BACK and you can keep the straps. That’s a promise. BUY WITH CONFIDENCE.
If you’re the type of hammock enthusiast that enjoys hanging with company, then the Foxelli Hammock Straps are the suspension system for you. These incredible daisy chains have a strength that surpass all the other products reviewed, and can hold 2,000 pounds. The triple-stitched polyester webbing won’t stretch or fray under the pressure of two bodies.
Together, the Foxelli straps boast 20 feet of combined distance and 40 connection points, making them long enough to hang just about anywhere. What’s more, the set of tree attachment loops will help you achieve the perfect hanging angle. Together, these elements contribute to eliminating frustration.
You won’t have to argue about who carries this hanging system. The entire bundle weighs less than a pound. It coils easily and fits into a handy stuff sack. With Foxelli, you can lean back and relax with your fellow outdoor enthusiasts.
- Length: Two straps totaling 20.4 feet
- Width: 2.2 inches
- Material: High-density polyester webbing
- Weight Capacity: 2,000 pounds
- 42 combined connection points make for easy adjustments
- Unmatched weight capacity
- Lightweight with complimentary carrying sack
- Double-stitched polyester webbing for enhanced security
- Long enough to hang pretty much anywhere
- Carabiners are not provided
Bottom Line: When traditional hammock suspenders don’t cut, the connection-heavy, 20.4-foot long Foxelli hammock straps are here to save the day. However, we can’t think of any reasons you’d want to send these babies back.
Wise Owl Outfitters XL Hammock Straps
- Be Nice to the Trees! These straps are tree friendly because they are 1 full inch wide. The strap sits flat on the tree so it will not damage it. If you are taking a hammock camping many camp sites will not allow you to use rope so be prepared with these straps. They work with hammocks like ENO Himal DoubleNest SingleNest & More.
- Fastest & Easiest Way to Hang Up Your Hammock! Unlike the other straps you will find on Amazon ours are very easy to use and you can have your hammock set up in under a minute. It is so easy even the kids can do it. You don’t have to tie a single knot. Works with all types of hammocks, double, lightweight, portable, parachute, polyester, ultralight, etc!
- 100% Satisfaction Guarantee - So you don’t have to wonder if you are risking your hard-earned money. If you don’t love them just let us know. We take great pride in taking care of our customers. Don’t take our word for it… just look at our reviews.
- Easily Adjustable and Won't Stretch - These straps are very strong and they will not stretch out. Move the included carabiner to any one of the loops to attain the perfect height and comfort level. Each strap is 10 feet long with 19 loops on each strap (many adjustments). Great for backpacking, no ties needed. Comes with its own carry bag for quick setup and easy hanging.
- Discounts!! That’s right. When you purchase these awesome Talon Straps you get great discounts on our other gear including camping hammocks that you can purchase too. Look for our discounts in the “Special Offers” section because when you bundle our gear you can save even more money.
Wise Owl’s Talon XL Hammock Straps are one of the most reliable and durable suspension systems on the market. The poly filament webbing offers risk-free suspension. Triple reinforced stitching offers users extra reassurance on overnight hangs.
We love that the strength of these straps can hold up to 500 pounds, so you shouldn’t find yourself wondering how you ended up on the ground. This makes them a viable suspension system for both single and double hammocks.
The lengthy strips and multiple connection points make for plenty of ease during setup. With so much wiggle room, you’ll never struggle to find a set of anchors. You can adjust the height and tension of the straps without having to deal with complicated knots.
This little pack is also convenient for those looking to reduce their pack weight. The entire bundle weighs just 15 ounces. It comes with a handy little stuff sack. What’s more, the wide, flat webbing is easy to coil.
- Length: Two 10-foot straps
- Width: 1 inch
- Material: Poly filament Webbing
- Weight Capacity: 500 pounds
- All gear weighs just 15 ounces
- 10-foot straps with 19 loops on each
- Straps are made from LNT-friendly polyester filament webbing
- Triple reinforced stitching for added security
- Not the most LNT friendly
Bottom Line: Wise Owl has jammed everything you ever need to hang a hammock into a little brown stuff sack.
Grand Trunk Hammock Suspension Straps
Best Straps for versatility
- MULTI-FUNCTION HAMMOCK TREE TRUNK STRAPS - Strong and lightweight colorful hammock straps are designed for the outdoors and will allow you to hang your hammock almost anywhere
- CUSTOM ADJUSTABILITY - Hammock straps offer more loops than most competitors with 36 combined adjustment points and a daisy chain design; Slap the straps on a big tree trunk, vehicle roof rack, porch post, big rocks, boat mast, or almost any anchor point
- QUICK AND EASY USE - Hanging up or tearing down your hammock has never been so quick and simple; No complicated knots; These straps are portable, convenient, offer a wide range of uses, and stuff neatly into the colorful stuff sack
- HIGH QUALITY AND DURABLE - Each of the 10' long daisy chain hammock strap offer more adjustment points to create the most comfortable and relaxing angle possible; 70 Nylon triple stitching insures the most comfortable and a secure hang;
- STRENGTH AND SPECS - Weighing only 12oz with a total weight capacity of 400 lbs; 1" wide straps are 10' long and PU coated poly webbing which allows Grand Trunk to offer a lifetime warranty
The Grand Trunk Tree Trunk Suspension Straps make up one of the most versatile hammock suspension systems on the market. These straps can be used to rig a hammock between trees, posts, vehicles, and other structures. On top of that, the Grand Trunk’s is strong enough to support both single and double hammocks.
The 36-point daisy chain makes it super easy to find viable anchor points. It doesn’t take much time to install or tear down these straps. You will spend less time fussing with tangled rope and more time enjoying your natural surroundings.
The poly filament webbing does an excellent job of fending of mold, mildew, and abrasion. This is a strong yet lightweight system that you won’t mind carrying in your gear pack. The including stuff sack makes transporting this versatile strap system even more effortless.
- Length: Two 10-foot straps
- Width: 1 inch
- Material: Poly filament webbing
- Weight Capacity: 400 pounds
- LNT-friendly tapered webbing
- The kit weighs just 12 ounces
- Multiple color options
- Covered by a lifetime warranty
- Must purchase suspension carabiners separately
If you want to brush up on more aspects of hammock camping then check out our following guides:
- We run down all there is to know about hammock camping for beginners.
- Learn 10 great knots for hammock pitching
- Learn how to hang a hammock correctly
- How to use hammock straps without damaging trees
Last update on 2021-01-24 / Affiliate links / Images from Amazon Product Advertising API