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[Display omitted] • Ninhydrin and Isatin-based chromogenic chemosensors selective for Cr3+ and Pb2+ ions were established. • NMR, FTIR, UV–vis and ESI-MS spectroscopy methods were used to confirm the probe and interaction of the probe with the analytes. • Probe L1 and L2 effective sense at colorimetric method was observed to be 2.80 × 10-6 M and 1.63 × 10-6 M detection limits. • Test Strip was designed to monitor the absorbance of Cr3+ and Pb2+ ions in real time analysis. • In a molecular logic circuit, the reversible and reproducible colorimetric switching off L1 and L2 was also discovered. A simple and easily synthesizable chromogenic small molecules probe L4 (2-(2-(benzo[ d ]thiazol-2-yl)hydrazono)-1H-indene-1,3(2H)-dione) and L5 (2-(2-(benzo[ d ]thiazol-2-yl)hydrazono)indolin-3-one) have been synthesized and characterized by various spectroscopy techniques such as FT-IR, NMR, and HRMS. The colorimetric naked eye detection of probe L4 showed a color change towards Cr3+ from orange color to pale yellow, whereas in case of L5 Pb2+ yellow to orange color was witnessed. The jobs plot analyses indicate the 1:1 binding stoichiometric for Cr3+ and 1:2 binding stoichiometric for Pb2+ ions with probes L4 and L5 respectively. The binding association constant (k a) values for L4 and L5 were found to be 6.651 × 10-5 M for Cr3+ and 6.493 × 10-5 M for Pb2+ ions. The limit of detection was found to be for Cr3+ (1.69 × 10−7 M) and Pb2+ (1.208 × 10−7 M) are far below than the limit set by the World Health Organization (WHO) for drinking water. Finally, the designed probes were applied for visible colorimetric test kits and real samples for rapid detection of Cr3+ and Pb2+ for all practical purposes, indicating their potential use in environmental samples. [ABSTRACT FROM AUTHOR]