
Sidr.io runs Sidr Tax, a fully managed US sales-tax compliance app for Shopify merchants.
Sidr.io, incorporated as BYOGCC, Inc., is a Y Combinator Spring 2019 company based in San Francisco that runs Sidr Tax, a fully managed US sales-tax compliance Shopify app launched in July 2022.
Its direct competitors include TaxCloud, Avalara, TaxJar, Quaderno, and Tax Rex; it is positioned as a filing-only service with no in-app calculation or collection and per-use pricing rather than bundles.
Sidr Tax is a fully managed US sales-tax compliance application for Shopify merchants. It covers nexus monitoring, state sales-tax registration, report generation, and automated filing and remittance to state websites, with a dashboard tracking nexus status across all US states.
The service integrates with Shopify to pull collected-tax data, generate per-state filing reports, and autofile returns on the merchant's designated filing frequency.
The post-Wayfair US sales-tax compliance market for e-commerce keeps growing as merchants owe tax in many states, and Shopify's own move into automated filing through Sovos is pulling more merchants toward integrated filing in 2026.
The segment is splitting between software-only calculators and managed, human-reviewed services, with small Shopify merchants still underserved by enterprise-priced tools like Avalara and Vertex, leaving room for managed per-use services. Streamlined Sales Tax participation and proactive nexus alerts are becoming key differentiators.
Sidr Tax markets itself as a fully managed, human-reviewed sales-tax service rather than software-only automation, with dedicated account management and average customer-support response times under one hour. Its pricing charges per filing and per registration rather than bundling, which it positions as more cost-effective for merchants than all-inclusive competitors.
The service also includes Colorado home-rule filings, notice management and resolution, and voluntary disclosure agreements at its premium tier, features that lower-cost self-service tools typically exclude.
Sidr Tax is a filing-only service: it does not calculate or collect sales tax, so merchants need Shopify Tax or a second app for that step, and it offers only a self-monitoring nexus dashboard rather than proactive nexus notifications. It also provides no audit support.
It works only on Shopify with no multi-channel or marketplace support, covers only US sales tax rather than global VAT, and its per-order pricing can accumulate at high volume, making it costlier than filing-only peers like Tax Rex for comparable functionality.
Sidr Tax uses usage-based pricing with no monthly subscription fee, no implementation costs, no onboarding fees, and no annual contracts. Its free plan covers nexus monitoring and CSV transaction imports, its Standard plan charges per filing and per registration, and its Premium tier is a custom-priced managed service with dedicated account management.
The per-filing and per-registration model lets merchants pay only for the states they actually file in, which the company contrasts with the bundle pricing of competitors like Avalara and Taxually.