The determination of salt content in crude oil is of great concern and the standard method from the American Society for Testing and Materials (ASTM) D 6470 is the most common for this purpose. This method is based on the extraction of salt to an aqueous solution using organic solvents, followed by chloride determination by potentiometric titration. However, several disadvantages have been reported, such as the excessive amount of reagents and waste generation, which contrasts with the recommendation of green analytical chemistry. Digital images can be an alternative approach using colorimetry on smartphones with low-cost and time-saving analyses. Thus, in this work, a digital-image-based method for chloride in crude oil was developed. The parameters for extraction (sample mass, time, temperature, and type of solvent) and for detection (ratio between silver nitrate and indicator, volume inside the vial, lighting, focal distance, number of pixels and pH effect) were evaluated. To obtain the digital images, an USB camera was attached to a homemade 3D-printed chamber with controlled light intensity by a white light-emitting diode (LED). Sample solution and reagents (silver nitrate and the indicator) were added to an Eppendorf vessel, which was placed inside the chamber. Thus, the digital images were captured and converted into red, green, and blue (RGB) histograms, and partial least square regression (PLS) model was obtained directly from the app. The PLS regression results were evaluated in terms of the number of samples and factors, the coefficient of determination (R2), the root mean squared error of calibration (RMSEC), the root mean squared error of cross validation (RMSECV), and the root mean squared error of prediction (RMSEP). The calibration curve (from 100 to 500 mg L-1 of Cl) was obtained using a PLS model with a R2 better than 0.99. No significant differences (p < 0.05) between the measured and predicted values were identified. The RMSEC, RMSECV and RMSEP of PLS model were of 9.04, 31.2 and 26.1 mg L-1, respectively. The detection limit was 69 mg L-1 (0.034 mg g-1 using 10 g of sample). No differences were observed (p < 0.05) when comparing the results from the proposed method with the reference values obtained using ASTM D 6470. The extraction method’s simplicity combined with the digital image-based colorimetric analysis allowed an easy-to-use and environmental friendly method. Other important advantages include low cost, the possibility to be portable, and high throughput in comparison to conventional methods.