Check if an email has a Gravatar image. View Gravatar avatars at different sizes and get the direct image link.

Calculate and compare AI GPU cloud rental costs across NVIDIA H100, A100, L40S, and RTX 4090 on AWS, RunPod, Lambda Labs, and GCP. Model Spot vs On-Demand savings.

View HTTP request headers and generate curl commands.

Learn about proxy types, validate proxy formats, and find free proxy lists.

Design digital Finite Impulse Response (FIR) filters online. Compare Hamming, Hanning, Blackman, Rectangular, and Kaiser windows, analyze main-lobe width, side-lobe attenuation, and export tap coefficients.

Calculate FFT bin resolution, observation time, processing gain, equivalent noise bandwidth (ENBW), and scalloping loss. Compare Hann, Hamming, Flat-Top, and Blackman-Harris windows.

Generate random fake addresses.

Validate email address format and syntax. Check for common typos, disposable domains, and formatting issues. Bulk validate multiple emails. Free online tool.

Check if an email address is valid, disposable, or from a major provider.

Audit SPF, DKIM, and DMARC DNS records to prevent spam folder placement.