You might’ve been thinking about leveling up your car stereo system for a while. It could seem like a daunting task when looking at all the technical aspects and the wide variety of options available.

That’s why in this car stereo buying guide, we’re providing you everything you need to know before buying one – see our top picks in all price ranges, buying advice, brands and FAQ below.

Best Car Head Units Table Comparisson

ImageDouble Din Head UnitProsConsSpecsBluetoothUSB InputAUX Input
Alpine CDE-172BT Bluetooth...
Our Pick
Single DIN

$129.95 at Amazon
Looks great, Price worthy, Packed with incredible featuresTedious set-up processAndroid Compatibility,
Works with Pandora® and Spotify,
iPhone, Color Customization, USB, Aux, FLAC, CD
Pioneer DEH-S5100BT in-Dash...
Under $100
Single DIN

$99.95 at Amazon
Smart phone control, User friendly controls, Navigation apps compatibilityInterface lighting makes it hard to see in daylightAndroid Compatibility,
Works with Pandora® and Spotify,
iPhone, Color Customization, CD
Pioneer AVH-3500NEX 1-Din...
Single DIN

$429.99 at Amazon
Hands free calling, Intuitive user interface, Bright display, Adjustable depth control of the screen, 7 inches screenTakes time to synced upApple CarPlay, Android Auto, AppRadio Mode+, Spotify®, Works with Pandora®, SiriusXM-Ready™, DVD, CD/CD-R/RW, MP3, FLAC, Siri Hands Free, Apple MapsYesRearRear
Pioneer AVH-2300NEX Multimedia...
Our Pick
Double DIN

$279.00 at Amazon
Quick smartphone connection, Large sized touchscreen, Lots of functional featuresNavigation may be a headache when using Apple CarPlayCD/DVD Receiver with 7" WVGA Display, Apple CarPlay, Android Auto, Built-in Bluetooth, SiriusXM-Ready and AppRadio Mode +YesRearRear
Pioneer AVH-210EX in-Dash...
Under $200
Double DIN

$146.00 at Amazon
Can't get better under $200, Great sound, Easy install, TouchscreenTiny volume buttonsBuilt-in Bluetooth, Hands-Free Profile (HFP), Audio/Video Remote Control Profile (AVRCP), Advanced Audio Distribution Profile (A2DP), Secure Simple Pairing (SSP), Serial Port Profile (SSP), and Dual Phone Connection YesRearRear
JVC KWR930BT Car Stereo -...
Under $100
Double DIN

$118.00 at Amazon
For this price it can't get better!Complex UIBluetooth, SiriusXM ready, 13-band graphic equalizer, MP3, WMA, WAV, AAC, and FLAC music files , Android and Apple ControlYesFrontFront
ATOTO A6 Double Din Android...
Android OS
Double DIN

$164.90 at Amazon
New brand but, really great head unit, providing you with everything you need in car stereo and even more! Just check out the reviews.No CD, DVDBuilt-in GPS receiver with an external antenna, Android(Wi-Fi) and Apple Control, Full HD 7" 1024*600 5-Touch Capacitive Touchscreen, Micro USB Drive/ Micro SD, Dual Bluetooth, Steering wheel controls

Single DIN Head Units

Our Pick

Alpine CDE-172BT

CD Player: Yes
RMS Power: 18 watts x 4 channels
Peak Output: 50 watts x 4 channels
Preamp Outputs: 6-channel 2V outputs (Front, Rear, Subwoofer)
Smartphone Features: Android and iPhone compatibility with Pandora Smart Sync accessibility
Bluetooth Compatible: Yes
USB Input: Front
AUX Input: Front

The Alpine CDE-172BT is our top picks for single DIN car stereos.

Want to take your commutes to the next level? Look no further. The CDE-172BT is what you’re looking for to enhance the audio quality in your vehicle.

It combines versatility with state of the art technology that is designed to cater to the needs of a real audiophile – see our complete Alpine CDE-172BT review here.

Car drivers expect their audio systems to deliver more than just amazing sound quality. A new head unit should be able to connect to a smartphone successfully, reduce noise to enhance the quality of calls and also add to the aesthetics of your car.

Under $100

Pioneer DEH-S5100BT

CD Player: Yes
RMS Power: 22 watts x 4 channels
Peak Output: 50 watts x 4 channels
Preamp Outputs: 3 Pairs (Front, Rear, and Subwoofer)
Smartphone Features: Android and iPhone compatibility with Spotify and Pandora Smart Sync accessibility
Bluetooth Compatible: Yes
USB Input: Front
AUX Input: Front

Buying a good CD receiver doesn’t have to cost a fortune. The Pioneer DEH-S5100BT is a budget-friendly (under $100) head unit with Bluetooth connectivity and smartphone computability, offering users so much more with decent sound quality – be sure to check out full specs of Pioneer DEH-S5100BT.

Whether you want to charge your smart device, create your own remixes or use the navigation options on your phone, this unit won’t let you down.

Under $100

Alpine UTE-73BT

CD Player: No
RMS Power: 18 watts x 4 channels
Peak Output: 50 watts x 4 channels
Preamp Outputs: 6-channel 2V outputs (Front, Rear, Subwoofer)
Smartphone Features: Android and iPhone compatibility with Pandora Smart Sync accessibility
Bluetooth Compatible: Yes
USB Input: Front
AUX Input: Front

The Alpine UTE-73BT is an affordable single-DIN mech-less receiver with all the basic features you might need. This unit is a great choice if you don’t use CDs anymore as an audio source or you don’t need to listen to them in your car and have alternative sources on the go – as we explain in full Alpine UTE-73BT review.

Alternatively, you can choose from other several sources supported by this receiver to access your music. With the AUX input, you can directly connect a digital player like an MP3 player. The USB port can read flash drives storing MP3, WMA, and FLAC files.

Touchscreen/Flip-Out Option

Pioneer AVH-3500NEX

RMS Power: 14 Watts x 4 Channels
Peak Output: 50 Watts x 4 Channels
Preamp Outputs: 6-channel 4V outputs (Front, Rear, Subwoofer)
Screen Size: 7 inches
Smartphone Features: Android Auto and Apple CarPlay
Bluetooth Compatible: Yes
Camera Input: Yes
USB Input: Rear
AUX Input: Rear

The Pioneer AVH-3500NEX (full review) offers you the capabilities of a double-DIN receiver in a single DIN size. It’s equipped with a single din flip-out screen to give you the ability to interact with your dashboard in the most user-friendly and intuitive way.

Being the only single DIN head unit to provide Apple CarPlay and Android a
Auto, this receiver provides high integration with your smartphone to let you access all its functionalities from your car’s dashboard.

Double DIN Head Units

Our Pick

Pioneer AVH-2300NEX

CD, DVD Player: Yes
RMS Power: 14 Watts x 4 Channels
Peak Output: 50 Watts x 4 Channels
Preamp Outputs: : 6-channel 2V outputs (Front, Rear, Subwoofer)
Screen Size: 7″ LCD touchscreen
Smartphone Features: Apple CarPlay Android Auto compatible, AppRadio Mode+, Siri Hands Free, Pandora and Spotify
Bluetooth Compatible: Yes
Camera Input: Yes
USB Input: Rear
AUX Input: Rear

The Pioneer AVH-2300NEX is a super sleek-looking, a double-DIN multimedia unit that has a long list of awesome features that set it apart from the competition.

This unit features a very wide, 7″ screen display with 800×480 resolution, an optional DVD player, and built-in Bluetooth. It’s also SiriusXM-ready and features AppRadio Plus, which allows you to access your smartphone from the screen – see all the specs in our full Pioneer AVH-2300NEX review.

It’s fully compatible with Apple and Android smartphones, along with iPod devices.

Under $200

Pioneer AVH-210EX

CD, DVD Player: Yes
RMS Power: 14 Watts x 4 Channels
Peak Output: 50 Watts x 4 Channels
Preamp Outputs: : 6-channel 2V outputs (Front, Rear, Subwoofer)
Screen Size: 6.2″ WVGA touchscreen display
Smartphone Features: Making calls, browsing music, accessing phonebook, and navigation options
Bluetooth Compatible: Yes
Camera Input: Yes
USB Input: Rear
AUX Input: Rear

The Pioneer AVH-210EX will give you the luxury of a touchscreen display without breaking the bank. It’s able to run most media file formats so you can listen to your favorite music and watch your favorite videos (DVD Player). Parking will also be easier when connecting a backup camera to the display.

The head unit comes with impressive illumination options to make your ride more exceptional. If you’re looking for a head unit under $200, then you should definitely check the Pioneer AVH-210EX.

Android OS Based


RMS Power: 24 Watts x 4 Channels
Peak Output: 45 Watts x 4 Channels
Smartphone Features: Available for connecting to Android smartphone(Wi-Fi option is only for Android 7.1 or down), and 1 option (Air-play) for iOS device.
Display: Full HD 7″ 1024*600 5-Touch Capacitive Touchscreen
GPS/Navigation: Builtin GPS Receiver module with external GPS antenna
Bluetooth Compatible: Yes
Camera Input: Yes
USB Input: Front
AUX Input: Front

The ATOTO A6 is a top-notch Android OS car system that’ll give access to all your media storage devices. You can cast your smartphone screen to its touchscreen display and benefit from its built-in WiFi and GPS antennas to directly access your navigation system.

Despite not having a CD/DVD player, this car stereo offers other options to access your media files. It can read Micro-SD cards through the SD slot.

It also has 3 USB ports and an AUX input to connect flash drives and different media devices – you can check all the specs of the ATOTO A6 in this full review.

Under $150

Sony WX920BT

RMS Power: 20 Watts x 4 Channels
Peak Output: 55 Watts x 4 Channels
Preamp Outputs: : 6-channel 2V outputs (Front, Rear, Subwoofer)
Smartphone Features: iPod, iPhone and Android devices compatibility, Pandora, Siri Eyes Free
Bluetooth Compatible: Yes
Camera Input: Yes
USB Input: Front
AUX Input: Front

For those who need something extra, the Sony WX920BT is an amazing car stereo. It’s an impressive unit that you can connect to two devices at the same time. It comes with a list of exciting audio features that will allow you to get the best of your new head unit.

The receiver supports audio playback for MP3, WMA, AAC, and FLAC formats. You can access your music files through the CD player, the USB port, or by directly connecting your audio devices through the AUX input – we also did a full Sony WX920BT review so be sure to check it out.

The USB input allows you to connect your Android device, iPhone, and iPod. It also has support for Pandora Internet Radio, so that you can control the app on your phone and discover great music using the receiver.

Under $100


RMS Power: 22 Watts x 4 Channels
Peak Output: 50 Watts x 4 Channels
Preamp Outputs: : 6-channel 2V outputs (Front, Rear, Subwoofer)
Smartphone Features: iPod, iPhone and Android control using the USB connection, Pandora, Spotify, and iHeartRadio
Bluetooth Compatible: Yes
Camera Input: No
USB Input: Front
AUX Input: Front

This JVC car stereo unit features a sleek and simple design that delivers decent output quality. It doesn’t break the bank but comes packed with interesting options that you can only find in more expensive models.

You can connect your iPhone and Android smartphone through the USB input for 1.5A high charging and audio control.

If you have an Android device compatible with AOA2 (Android Open Accessory), you can connect it in the plug and play Audio Mode to simply play the audio files on the device – as we mention in the full review of the JVC KW-R930BTS.

You can also use the JVC Music Play app to access the Auto Mode and get more control over your files including folders navigation and search.

Things to Consider Before Buying a Car Stereo


Car stereos vary greatly in price, depending on the features and quality of sound they offer. You can find stereos for as low as $20 and up to $600 or even more for the high-end options.

You can find head units with touchscreen displays for less than $100. However, don’t expect it to be highly responsive. It might not include good equalizer options as well. On the other hand, you can find units with LCD displays for more than $150 but include much better features like dual Bluetooth, support for Apple CarPlay and Android Auto, and built-in amplifiers.

Overall, it’s a trade-off. You can find very good stereos at low prices if you’re willing to abandon some features you don’t need. The more accurate you know what features exactly you need, the better is your chance of finding the best deal for you.

While searching for your new car stereo, you must make sure that it fits your car and that it’s equipped with all the features you need. However, the available options could be overwhelming so we’re breaking it all down for you.


Head units come in different sizes, some are standard sizes, while others aren’t. The stereo openings in the car’s dashboard are manufactured to accommodate the standard sized head units.

They’re based on the DIN 75490 (Deutsches Institut für Normung) standard, put in place by the German national organization for standardization. It was later adopted by the International Organization for Standardization in 1984 as ISO 7736.

The most important thing to check before looking for a stereo is the size of opening your car has and what types of stereos it could house so that you could look for a compatible head unit – you can read more in our full explanation of single din vs double din unit.

There are two main standard sizes of stereos according to ISO 7736:

Single DIN

The Single DIN stereo opening has a size of 7’’ Width x 2’’ Height. The head unit is compact in shape and usually has a CD or DVD player but not enough space for a display or a touch screen. However, some brands offer single DIN stereos with flip out motorized touch screens.

Double DIN

The Double Din stereo is twice as tall as the single DIN. The opening measures 7” x 4”. Stereos of this size normally feature large color touch screen displays for options such as video playback, GPS navigation, rearview camera monitoring, and cell phone mirroring.

Commonly, cars with dashboards that have single DIN stereos installed only support this size, with few exceptions where the dashboard can house a double DIN stereo.

On the other hand, cars with double DIN stereos installed are also able to support single DIN stereos by using a bracket kit to install the single head unit and use the additional space for other devices like storage space or equalizers.

1.5 DIN Stereo

The 1.5 DIN is a non-standard size for car stereos. It measures 7’’ x 3’’, which is longer than a single DIN. It can be replaced by both 1.5 DIN and single DIN head units. In some cases, there’s enough space under the bezel surrounding the unit that could fit a double DIN stereo.

Car In-Dash Mounting Kits

The car stereo dash mounting kits are used so that you can replace your car’s factory stereo with a new stereo of a different size. For example, you can use a dash kit to replace a double DIN stereo with a single or 1.5 DIN. You either attach the kit to the dash then install the stereo in it or you secure it to the stereo and screw both of them to the dash.

What Head Unit Will Actually Fit in Your Car?

There are mainly two ways to find the right size of a stereo that could fit in your car.

The first option is to use a car stereo size database. These databases are provided by car audio retailers and they contain info about which size of head units fit in specific models of cars. You can find these databases online. All you need to do is to use the lookup tool to enter the maker, model, and year of your vehicle, and it’ll give you the head units that fit in your car.

One of the popular tools is Pioneer Electronics Fit Guide

The other option is to physically measure the head unit yourself. Once you know the length of your head unit, you can replace it with another one of the same size or a smaller size using the appropriate dash mounting kit.

When you’re taking the measurement, make sure to remove any trim pieces, bezels, or additional components in order to get the right dimensions of the unit. You might be lucky to discover that your car has a spacer or a pocket that lets you install a double-DIN stereo despite originally coming with a single DIN one.

Types of Car Stereos

Car stereos are divided into several types based on the main functions they possess and the media sources they support.

CD Player

A CD receiver has the ability to play audio CDs and recordable discs. It’s also mostly able to play MP3, WMA (Windows Media Audio), and AAC files.

Due to the fact that CDs are almost obsolete, most people have their music on their phones or on USB sticks. Therefore, most CD players support USB and Bluetooth or wireless connectivity so that you can connect your smartphone to your car’s audio system.

DVD Player

A DVD receiver is the same as the CD receiver but includes more functionality and support for more media and entertainment systems. It has the ability to play DVDs. That’s why it usually includes a touchscreen in order to allow for video playback.

It’s more expensive than the CD receiver. However, it’s a less expensive choice than the navigation receiver, if you want to have the touchscreen without built-in GPS.

Digital Media Receiver

This receiver – also called mechless receiver – is becoming more common in new cars. It doesn’t have built-in CD players as most people don’t own CDs anymore.

Instead, the receiver offers various other features like USB inputs, auxiliary inputs, SD card slots, and wireless connections. It can connect to almost all smartphones and other kinds of digital media storage devices. A radio receiver might also be included with connections for satellite radio tuners as well.

Navigation Receiver

This receiver is the same as a DVD or a digital media receiver, with the added capability of the built-in navigation system through satellite GPS. It offers larger and more accurate coverage than navigation systems found in smartphones, which are based on cellular towers.


Head units usually rely on two or three power inputs. The two main ones are a constant and a switched power source.

The constant 12V power source is always connected to the stereo’s memory to preserve its presets and clock settings so you don’t lose them when you turn off the car itself.

The switched power input provides the stereo with the main power to function and it’s switched on when you start the car with the ignition key. This prevents the car’s battery from being drained when it’s off.

Third power input for illumination is sometimes found. It’s connected to the dimmer functionality for the headlights and the dash light.

The stereo connects to the speakers through a pair of wires (positive and negative) for each speaker in order to drive it. When replacing your head unit, you must make sure that the new one has a sufficient power rating to drive your speakers.

The RMS (Root Mean Squared) power rating is more essential here than the peak power rating. It gives an indication of the continuous output power the stereo can consistently handle.

Preamp Outputs

The preamp stage happens before the amplification stage. It takes the low-level raw signals of the head unit and processes them before being sent for amplification and then to the speakers.

The preamp gives you various controls over the output signal like volume levels, tone controls including bass and treble, equalization, fader, time correction, and crossovers.

All these sound adjustments are outputted from the preamp to the amplifier. It also allows external amplifiers or a subwoofer to be connected to drive the speakers.


The display can either be a small one (mostly on single DIN) with just one or two lines just to show some info like the song currently playing, the album and the artist plus other limited settings or it can be a large touchscreen display (double DIN ), which gives you lots of options and makes it easier to control.

What Functions Do You Need?

Modern car stereos are equipped with an abundance of functions and features that leverage the user’s experience – we explain each of them in more detail below.


99% of head units are equipped with a radio receiver that supports the two broadcasting modulations. FM has a better sound quality than AM.

Android™, iPod®, and iPhone® Support

The stereo provides support for Android phones, iPods, or iPhones. It allows for easier access to the devices’ music apps, media storage, and file managers. Phone calls and messages functions are also available. In the case of iOS devices, the files can be navigated through using Siri voice commands. It also charges the phone while it’s plugged in.

USB Inputs

The USB input ports allow the reading media files and music stored on a variety of USB devices like phones, flash memories, and MP3 players. These are good options to have your music library with you all the time.

SD Card Slots

Another way to store your music is on the small SD cards. Some stereos include readers for such cards.

Auxiliary Inputs

Auxiliary inputs allow connecting to plug-and-play devices like satellite radios and phones. The connection uses the standard headphone jack. It either goes to the front panel of the head unit or through a rear cable.

Bluetooth® Connectivity, Bluetooth® Audio Streaming

The Bluetooth connection can be used for hands-free calling with cell phones – as simple as that. In addition, some stereos also support wireless audio streaming through Bluetooth using phones and other media players. On the other hand, if you’re just upgrading and want to add Bluetooth capability to your current car stereo there are still options.

Apple Carplay, Android Auto

These are the mobile mirroring features for both iOS and Android devices, respectively. They allow you to control your smartphone through the head unit’s touchscreen or through voice commands.

Native supported apps include the phone, SMS, music streaming, GPS navigation, and web search. They can also run additional third-party apps like audio content providers like Spotify and messaging apps like Whatsapp. The mirroring is established on both wired and wireless connections.

GPS Navigation

Head units with navigation receivers include a built-in system based on satellite GPS – these are usually the pricier ones.

Backup Camera

You get the option to add a backup camera at the rear for parking assistance and rear visibility. The stream from the camera could be displayed on the stereo’s screen.

Pandora® Internet Radio

A stereo with the Pandora radio feature allows you to access the internet radio service to stream your playlist or discover new music. The Pandora app on your phone is controlled using the app control mode when your smartphone is connected to the stereo through USB or Bluetooth.

Satellite Radio

“Satellite radio-ready” head units feature an input that can be connected to a satellite radio tuner. The SiriusXM satellite radio could also be accessed through “SiriusXM Ready” units. It offers over 140 channels. You can also connect a portable satellite radio to your car stereo using auxiliary input.

HD Radio™

These are radio stations broadcasting high definition content using digital signals. They have better sound quality and less noise than AM/FM stations. Only a stereo with an HD radio tuner can receive these HD stations.

Best Car Stereo Brands


This name is a legend in the car audio community, representing one of the very first premium choices for a so-called “aftermarket” radio that installers everywhere endorsed and recommended. While Alpine has gone on to manufacture excellent products in other areas such as amplifiers and speakers, the company’s reputation remains attached to its legendary head units – and the current lineup is a testament to that.

Today, Alpine offers the CDE-172BT advanced Bluetooth CD receiver, ILX-107 seven-inch in-dash receiver with wireless Apple CarPlay, CDE-175BT CD/USB receiver with advanced Bluetooth, UTE-73BT advanced Bluetooth digital receiver and a host of others.


Perhaps one of the most historically-rich brands on this list, JVC (the Japan Victory Company) has been manufacturing electronics of all kinds for generations, and in the world of car audio, its efforts are as impressive as its legacy.

JVC’s current head unit lineup consists of models for both marine and motorsports applications in addition to multimedia and in-dash products, with the more popular variants being the KD-T905BTS CD receiver, KD-R995BTS CD receiver, KD-T9000BTS CD receiver, KW-V950BW multimedia receiver, and KW-V940BW multimedia receiver.


A name as recognizable as Alpine when it comes to quality head units, Kenwood went from manufacturing all manner of high-performance home hi-fi and home theater components to focusing solely on mobile audio products, the company’s head units becoming highly sought-after by serious car audio competitors. Kenwood offers an almost overwhelming number of receivers for a myriad of applications, from network navigation and multimedia to marine, digital media, single DIN and double DIN installs.

Amongst the models popular with serious car audio buffs are those in the flagship eXcelon series, including the much-heralded DNX696S navigation DVD receiver with Bluetooth and HD radio.


Another brand offering a nearly infinite amount of options in the area of head units and receivers, Pioneer divides its products into GPS navigation, NEX line, DVD receivers, CD receivers, and digital media receivers groupings, the new line of DVD receivers offering a wide range of entertainment and connectivity options for the drive.

Amongst these new products, Pioneer has been excited about standout models such as the AVH-1550NEX multimedia receiver, AVH-210EX multimedia DVD receiver, and AVH-211EX multimedia DVD receiver.


As one of the more value-oriented car audio companies on the market focused on redefining the phrase “bang for the buck,” Jensen has grown from a manufacturer mainly interested in offering economically-priced subwoofer enclosures and amps to a formidable entity in the aftermarket head unit sector.

Today’s Jensen lineup consists of models like the VX7024, VX7020 multimedia touchscreen double-DIN receiver, VX7528 double DIN DVD navigation receiver and VX7012 flip-out navigation screen with Sirius tuner package.


Does this brand even need an introduction? Renowned for its home and mobile audio products as well as its highly-respected televisions, disc players and more, Sony has literally transformed the electronics landscape, offering the serious car audio enthusiast and competitor everything from amplifiers and speakers to hard-hitting subs and serious head units.

Featured products currently marketed by the electronics giant include the XAV-AX100 media receiver with Bluetooth, RSX-GS9 receiver, MEX-GS820BT and XAV-AX5000 media receiver with Bluetooth and CarPlay/Android.


BOSS Audio Systems is celebrating more than 30 years of creating excellent products, always offering knowledge, innovation and great customer service to its clients and partners. As a featured item currently making the rounds at mobile audio shows and in retail stores, BOSS’ BVCP9685A multimedia player boasts everything cutting-edge – from Apple CarPlay and Android support to Bluetooth functionality. With 80 watts into four channels max power onboard and a bright 6.75-inch touchscreen, the 9685 is poised to become a favorite amongst mobile electronics techies.

Car Stereo FAQs

Why do I need a new car stereo?

The new aftermarket stereo can give you better sound quality and controls than the factory stereo that came with your car. It’ll also include plenty of additional features.

How much does it cost to install a car stereo? Can I do it myself?

There is no specific cost for the installation of a new stereo. There’s the cost of the audio component itself plus the installation fee in case it’s done by a professional. You can also upgrade additional parts like speakers and amplifiers. All this could range from about $100 to thousands of dollars.

It’s possible to install the stereo yourself by following one of the many guides found online. You just need to have the right tools. However, it’s not always straightforward, so it’s better to rely on an expert if you’re in doubt.

How do I adjust the car stereo system for best sound?

You can get a better sound from your car audio system by installing amplifiers, equalizers, and subwoofers. They’ll give you more control over the power and frequencies of the output sound. You can use them to adjust the gain and tone controls to get the cleanest sound.

Car Stereo Troubleshooting (most common problems)

Most of the common problems people face with car head units happen due to bad wiring and poor grounding. Always check your power and speaker’s wires first and make sure you have an adequate ground connection.

Vincent Talbot

Last update on 2020-04-05 / Affiliate links / Images from Amazon Product Advertising API