# TKS-API LICENSE ## TKS Ephemeris Suite License — Independent Astronomical Computation & Pañcāṅga Engine ### Version 1.0 Copyright © 2026 Acharya Rajesh Benjwal (आचार्य राजेश बेञ्जवाल) / Tantrakulam (Prithvi Foundation Trust) These terms govern access to and use of the **TKS Ephemeris Suite** — including the `tks-ephemeris` engine, its HTTP/JSON API, the standalone web pages (Pañcāṅga, Eclipse, Ākāśa, Sun, Moon, Solar system, Planets, Udaya-asta, Festivals, Lab, API), compiled forms, documentation, kernels glue, original tables and related operator materials (together, the “Software”). The ancient astronomical siddhānta texts, public-domain astronomical facts, and mathematical concepts are **not** claimed as proprietary. What is protected is the Licensor’s **source code, implementation, API, original tables, engineering, documentation, branding**, and related materials. NASA/JPL DE kernels are used as reference state data under their own terms and are not redistributed by this licence. --- ### 1. Definitions **Licensor** means Acharya Rajesh Benjwal / Tantrakulam (Prithvi Foundation Trust). **Licensee** means the person or organisation that uses the Software or API under a valid API key or written licence. **Software** means the TKS Ephemeris Suite, its engine (`tks-ephemeris`), API routes (`/v1/tks/*`, `/v1/ss-*`, `/v1/lab/*` and related), web pages, compiled binaries, tables, and documentation. **Commercial Use** means any use that is revenue-generating, paid, subscription, advertising/sponsorship-supported, business, client-facing, or that forms part of a commercial app, website, SaaS, temple/consultation product, horoscope product, media, or other commercial service — whether the API is exposed to end users or hidden in a backend. **Non-Commercial Use** means personal, educational, academic-research, or other genuinely non-commercial open projects that are not Commercial Use. **Free Basic API** means the `basic` plan: limited quota, core Pañcāṅga and basic planetary positions, with mandatory attribution. **Commercial License** means a paid annual TKS-API commercial grant (`commercial` or `enterprise` plan, or a written agreement). --- ### 2. Ownership and Intellectual Property The Software, API implementation, algorithms **as implemented**, source code, compiled binaries, calculation tables, proprietary constants, documentation and branding remain the property of the Licensor. Nothing in this licence transfers copyright in the Software. Sūrya-siddhānta and other classical texts, and uncopyrightable facts of astronomy, are not asserted as the Licensor’s exclusive literary property. Individual contributors retain copyright in their contributions as recorded. The historical **benchmark results** and the **whitepaper** may be cited with attribution; the underlying engine and code remain protected. --- ### 3. Free Basic API License Subject to these terms, the Licensor grants a worldwide, non-exclusive, non-transferable, revocable licence to use the Free Basic API for **Non-Commercial Use only**. Default quota (may be changed by the Licensor): **1,000 API requests per calendar month**, with a per-minute burst cap. Included: tithi, nakṣatra, yoga, karaṇa, vāra, sunrise/sunset, basic planetary positions, and the public TKS web pages. Not included: kundali, muhūrta, bulk historical/yearly print, eclipse reports (PDF), Engine-B deep-time batches, or any Commercial Use. --- ### 4. Permitted Non-Commercial Use Non-commercial researchers may use the Basic API for academic research, teaching and scholarly analysis, and personal study, provided access limits and attribution are respected. Publishing results of research done with the engine is permitted with attribution. --- ### 5. Prohibited Use Licensee may not, without a separate written agreement: - use the Free Basic API for Commercial Use; - resell, sublicense, redistribute, mirror, clone, expose, or provide the API as an independent competing astronomical, pañcāṅga, or ephemeris service; - extract bulk API results, tables, or derived datasets to build a competing astronomical/pañcāṅga database or service; - reverse engineer, decompile, or attempt to extract source, keys, kernels glue, or unpublished constants from hosted binaries or the API (except where mandatory law cannot be waived); - remove, obscure or falsify required attribution, or claim the Software as one’s own; - share, publish, or leak API keys; or - circumvent rate limits, licence checks, or access controls. --- ### 6. Commercial Use Commercial Use is **not** granted by the Free Basic API. If the Licensee (or a product the Licensee operates) is Commercial Use, a valid **Commercial License** is required — even if the API is not resold and is used only internally as a calculation backend. --- ### 7. Commercial License Requirement **Non-Commercial Use is permitted under the Free Basic API terms. Commercial Use requires a valid Commercial License.** A Commercial License is typically issued annually and may record application ID, company, domain, package ID, API key, monthly quota, and expiry. Developer and Pro keys are technical access tiers; they do **not**, by themselves, authorise production Commercial Use. --- ### 8. API Keys and Rate Limits Access is keyed. Typical published quotas (operator may adjust): | Plan | Typical credits / month | List price | Commercial production | |------|-------------------------|------------|------------------------| | Free Basic | 1,000 | ₹0 | No | | Developer | 10,000 | ₹4,999 / year | No (dev/test only) | | Pro | 50,000 | ₹14,999 / year | No (research / non-commercial) | | Commercial | 250,000 | ₹36,000 / year | Yes (annual) | | Enterprise / Admin | Unlimited | from ₹1,20,000 / year | Yes (written terms / SLA) | The running service enforces plan, scope and rate limits. Exceeding a quota may yield HTTP 429. Keys may be suspended for breach. --- ### 9. Redistribution Licensee may not resell, sublicense, redistribute, mirror, clone, expose, or provide the API as an independent competing service without a separate written agreement. This prohibition covers the engine, the API, and derivative engines. --- ### 10. Bulk Data Extraction Calculated facts in a single ordinary response are not claimed as copyrighted literature. The Licensee nevertheless agrees not to bulk-extract, harvest, or cache API results, proprietary metadata, diagnostic information, kernels-derived state, or derived datasets in order to build a competing astronomical or pañcāṅga database or service. --- ### 11. Reverse Engineering Licensee shall not reverse engineer, decompile, or attempt to extract source, keys, or unpublished constants from hosted binaries or the API, except to the extent that mandatory law cannot be waived. --- ### 12. Derivative Works Non-commercial wrappers that call the API and preserve attribution are allowed under the Free Basic terms. Shipping a competing engine, cloned API, or commercially distributed derivative of the source requires a written licence. --- ### 13. Attribution Free Basic, Developer and Pro: the Licensee must display, in documentation or UI reasonably visible to end users: > Astronomical engine by Tantrakul — TKS Ephemeris (Acharya Rajesh Benjwal) or > Powered by TKS Ephemeris (Tantrakul) Commercial License: attribution is optional by default (white-label permitted) unless the written grant says otherwise. --- ### 14. Enterprise Licensing Enterprise terms (custom quota, SLA, support, named domains, white-label) are only those set out in a written agreement with the Licensor. --- ### 15. Fees and Renewal Developer and Pro fees are typically monthly; the Commercial License is typically **annual** and expires unless renewed. Fees are as quoted at the time of grant. Non-payment may suspend the key. --- ### 16. Suspension and Termination The Licensor may suspend or terminate a key for breach, abuse, non-payment, or legal risk. On termination the Licensee must stop calling the API. Sections on ownership, disclaimer, liability, and bulk-extraction survive. --- ### 17. Disclaimer of Accuracy The Licensor does **not** warrant that calculations will exactly match any particular modern ephemeris (e.g. NASA/JPL, Swiss Ephemeris), any particular traditional pañcāṅga, or any regional religious calendar. - **Engine A** computes within JPL DE coverage with stated reductions; **Engine B** is an **approximate N-body reconstruction** (the live route is capped at ≈ ±20 yr; the offline CLI integrates much farther), and results are **not** equivalent to modern observational ephemeris accuracy — uncertainty grows with span. - Eclipse magnitude/contacts and Saros are model outputs; the classical/shāstrīya orbs and the equilibrium tide are theoretical. **Actual local sea level** requires bathymetry + ocean dynamics and is shown, where present, from an **external model** (equilibrium tide ≠ actual local sea level). - Results follow this engine’s implementation, conventions, and place/time inputs. --- ### 18. No Warranty The Software and calculations are provided **“AS IS”** and **“AS AVAILABLE”**, without warranties of accuracy, fitness for a particular purpose, uninterrupted availability, or error-free operation. --- ### 19. Limitation of Liability To the maximum extent permitted by law, the Licensor is not liable for indirect, incidental, special, consequential, or punitive damages, or lost profits, arising from use of the Software or API. --- ### 20. Indemnification Commercial Licensees shall indemnify the Licensor against claims arising from the Licensee’s product, marketing, ritual advice, or combination of the API with third-party data, except to the extent caused by the Licensor’s wilful misconduct. --- ### 21. Third-Party Software The Software may bundle or call third-party components (for example, Three.js, D3, world-atlas, Open-Meteo Marine) under their own licences. Those licences continue to apply to those components. NASA/JPL DE kernels are used as reference state data under their terms. --- ### 22. Changes to License The Licensor may publish a new version of these terms. Continued use after notice constitutes acceptance of the version then posted, except that a paid annual Commercial License follows the version in force at purchase unless the written grant says otherwise. --- ### 23. Governing Law These terms are governed by the laws of India. Courts at Dehradun, Uttarakhand, have exclusive jurisdiction, subject to mandatory consumer protections where they apply. --- ### 24. Contact Tantrakulam / Prithvi Foundation Trust 138, THDC Colony Banjarawala, Dehradun, India info@tantragurukul.org https://panchang.tantragurukul.org/