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Contents

🔑 Authentication

Auth via URL parameter

🔗 End point

📥Request parameters

Supported formats

✅ Example request

📦 Response structure

⚠️ Error codes

📈 API limits & billing

🛠️ API Manager

🔒 Security

🧼 Notes for developers

🆕 Changelog

V2.0 – qConv.com Converter - API Documentation

With the qConv Converter API you can convert colors between different formats - including RGB, HEX, CMYK, PANTONE®, RAL, HKS, NCS and custom manufacturer palettes.

🔑 Authentication

The qConv API uses API keys, which you can manage via your profile.

Auth via URL parameter

GET /api/v2/convert.php?from=hex&input=FF0000&to=ral&apikey=[YOUR_API-KEY]

Note: The key is Base64URL-encoded (URL-compatible) and secure.

🔗 End point

GET https://qconv.com/api/v2/convert.php

📥 Request parameters

Parameters Type Required Description
from string ✅ Yes Source format of the color, e.g. rgb, ral or manufacturer names such as behr
input string ✅ Yes Input value, e.g. FF0000
to string ✅ Yes Target format of the color, e.g. hex, cmyk or manufacturer name such as Caparol Color
apikey string ✅ Yes Your personal and secret API key

Supported formats

Color formats

rgb hex cmyk pantone ral hks ncs sw

+ Manufacturer colors

All manufacturer codes that you can find on the manufacturer pages under the following link are valid values.

https://qconv.com/en/manufactures

Look for the API code reference or this symbol in the left-hand column on the manufacturer's website:

✅ Example request

Hex to rgb

GET /api/v2/convert.php?from=hex&input=FF0000&to=rgb&apikey=[YOUR_API-KEY]

Answer:

{
    "api_version" => "v2",
    "timestamp" => "2025-08-14T13:28:00+01:00",
    "http_response_code" => 200,
    "from": "hex",
    "input": "ffa500",
    "to": "rgb",
    "result": "255 165 0",
    "name": "Orange",
    "more_conversions": {
        "pantone": "185",
        "ral": "3026",
        "hks": "10",
        "rgb": "255 0 0",
        "hex": "#FF0000",
        "cmyk": "0 100 100 0",
        "sw": "2910",
        "ncs": "S1085-Y90R"
    },
    "user_data": {
        "username": "USER #12345",
        "used tokens": 1,
        "max tokens": 50,
        "percentage used": "2 %"
    }
}

rgb to Manufacturer color BEHR

GET /api/v2/convert.php?from=rgb&input=145, 25, 100&to=behr&apikey=[YOUR_API-KEY]

Answer:

{
    "api_version" => "v2",
    "timestamp" => "2025-08-14T13:28:00+01:00",
    "http_response_code" => 200,
    "from": "rgb",
    "input": "145, 25, 100",
    "to": "behr",
    "result": "p120-7 glitterati",
    "deltaE00": "11.2"
    "match_percent": "93.1%",
    "more_conversions": {
        "pantone": "7649",
        "ral": "4006",
        "hks": "28",
        "rgb": "145 25 100",
        "hex": "#911964",
        "cmyk": "0 83 31 43",
        "sw": "6842",
        "ncs": "S3055-R30B"
    },
    "user_data": {
        "username": "USER #12345",
        "used tokens": 2,
        "max tokens": 50,
        "percentage used": "4 %"
    }
}

📦 Response structure

Field Type Description
api_version string Returns the currently used version of the API, e.g. 'v2'
timestamp string Timestamp of the request in ISO 8601 format, e.g. '2025-08-14T13:42:00+01:00'
http_response_code string HTTP status code of the response (e.g. 200, 400, 500). Indicates whether the request was successful or returned an error
from string Transmitted output format
input string Transmitted original value
to string Transmitted target format
result string The converted result
name string/null Color designation for Sherwin Williams, NCS (German), HEX (if available), RGB (if available)
deltaE00 string/null Different between the colors as DeltaE2000 value (ΔE₀₀). Further explanations of Delta E 2000 or dE₀₀ can be found in the table below.
match_percent string/null Note on color matching when searching for the matching manufacturer color in percent. E.G.: 'match_percent': '92.2%',
Only output when converting to manufacturer colors.
more_conversions object All other available parallel conversions as an array
user_data object Information about your API account, such as the number of conversions used.
error string If an error occurs: Object with further details such as error code, description, etc. If the request is successful, this field is zero or not present

ΔE₀₀ and the meaning of the values

ΔE₀₀ Description Perceptibility by humans
< 0.5 Imperceptible The color difference is not visible to the human eye.
0.5 – 1.0 Very low deviation The color difference is only perceptible under laboratory conditions.
1.0 – 2.0 Minor deviation The color difference is barely visible, usually acceptable.
2.0 – 3.0 Perceptible deviation The color difference is visible in direct comparison.
3.0 – 5.0 Significant deviation The color difference is clearly visible, possibly problematic.
> 5.0 Strong deviation As different as two different colors.
Further information on ΔE₀₀₀, Delta E 2000 or dE₀₀₀ can be found here: DELTA E 2000 WIKI

⚠️ Error codes

Status code Meaning
400 Missing or invalid parameter
401 Invalid or missing API key
429 Monthly API limit reached
500 Internal server error

If the API key is missing or an incorrect API key has been entered:

{
    "api_version" => "v2",
    "timestamp" => "2025-08-14T13:28:00+01:00",
    "http_response_code" => 401,
    "error": "Unauthorized",

}

If an entry is missing or a non-compliant value is entered:

{
    "api_version" => "v2",
    "timestamp" => "2025-08-14T13:28:00+01:00",
    "http_response_code" => 400,
    "error": "Missing input, from or to" | "Conversion failed or input invalid",
    "user_data": {
        "username": "USER #12345",
        "used tokens": 50,
        "max tokens": 50,
        "percentage used": "100 %"
    }
}

📈 API limits & billing

Each API key has a monthly limit. Free are 50 tokens per month per API key. Up to two API-KEYs can be created free of charge.

This can be extended by upgrades:
With the Basic-API tariff you can create 5 API-KEYs with 200 tokens each (∑ 1.000 tokens).
With the Premium API plan, you can create 10 API-KEYs with 1.000 tokens (∑ 10,000 tokens).
With the Voyager API tariff, you can create 50 API-KEYs with 10,000 tokens each (∑ 500,000 tokens).
If you have special requirements, we can also prepare user-specific offers at any time. Please feel free to contact us.

When the limit is reached:

{
    "api_version" => "v2",
    "timestamp" => "2025-08-14T13:28:00+01:00",
    "http_response_code" => 429,
    "error": "Hello USER #12345, your monthly API quota of 50 requests has been used up. Please contact [email protected] to upgrade or wait for the next reset.",
    "user_data": {
        "username": "USER #12345",
        "used tokens": 50,
        "max tokens": 50,
        "percentage used": "100 %"
    }
}

🛠️ API Manager

Manage API keys (add/delete)

View total and API-related usage

Increase limits per month through upgrades

Generate new keys (Base64URL-safe)

Add comments for better differentiation

🔒 Security

All parameters are sent via GET

Rate limiting per key optional

32 byte long Base64URL key

🧼 Notes for developers

All parameters are case-insensitive

Hex code is not possible with #: Only FF0000 are valid

255,0,0 or 255 0 0 for RGB

185C and 185 C work for PANTONE

Support

Note: For technical reasons, it may happen that no results are displayed for some manufacturer names. If you need help or your conversion does not work for any other reason not mentioned, please contact us at info[at]qconv.com. We offer support for customers from the 'Basic API Service'.

🆕 Changelog

API-V3.0:

  • NEW: There is the possibility to get the respective related colors such as complementary, lighter, darker, warmer, colder, etc. for transmitted colors. We have created /api/color.php for this purpose.
  • LAB and HSL color integrated in the answer
  • In the object user_data we have standardized the identifier 'used tokens' with an underscore.
    NEW: 'used_tokens'
  • In the object user_data we have standardized the identifier 'max tokens' with an underscore.
    NEW: 'max_tokens'
  • In the object user_data, we have standardized the identifier 'percentage used' with an underscore.
    NEW: 'percentage_used'

2025-10-21

API-V2.0:

  • Color differences are now also output as a color difference value in dE00 format (Delta E 2000) when converting to the manufacturer
  • If there is a color designation (Sherwin Williams, NCS (German), HEX or RGB), this is output
  • API version number and timestamp are also output
  • In the event of an incorrect entry, more detailed information about the reason is provided

2025-08-14

API-V1.0:

  • API integrated into the website

2025-07-15

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