Z.ai (ChatGLM)
Z.ai is Zhipu AI's chat and developer platform built on the GLM model family (formerly ChatGLM), and one of the fastest-moving labs of 2026. Basic chat on GLM Flash models is free and unlimited, while the flagship GLM-5.x reasoning models -- which rival Opus-class systems on agentic and coding tasks -- come via cheap coding-plan subscriptions (from ~$10/mo) or a very low-cost API. Developers get a strong, English, OpenAI-compatible platform with genuinely free Flash models, not just trial credits. The catch is China jurisdiction and PRC-aligned content rules, plus fast-shifting pricing.
Pi
Pi, from Inflection AI, is an empathy-first 'personal AI' tuned for supportive, natural conversation and voice rather than tasks. It's free with no paid consumer tier (now with some message caps), works across web and mobile, and has a uniquely warm, low-friction tone with eight voices. But after Inflection's founding team left for Microsoft in 2024 and the company pivoted to enterprise, Pi has sat in maintenance mode -- it still runs reliably, but the roadmap is uncertain and the feature set is frozen. It's lovely for companionship, but not something to build a workflow on.
Z.ai (ChatGLM) edges Pi on aggregate — 88 vs 56.
The best price-to-performance AI chat and API of 2026 -- free unlimited Flash chat and near-frontier paid models for cents, if your org is comfortable with a China-based provider. Pi still wins for buyers who prioritise genuinely free, no card, no paid upsell. Both tools are independently scored — the right pick depends on which dimensions matter most for your workflow.
Side-by-side, every cell sourced.
Pricing pulled from each tool's public site. Scores follow the BigBang Score rubric — pricing transparency, free tier, API support, update frequency, unique factor, documentation, and community.
Use-case picks.
Cut through the spec sheet. Here's what we'd recommend depending on what matters most.
Pick Z.ai (ChatGLM) if…
You prioritise unlimited free chat plus genuinely free api models and flagship glm-5.x rivals opus-class at a fraction of the cost.
Pick Pi if…
You prioritise genuinely free, no card, no paid upsell and best-in-class empathetic tone and natural voice mode.
Editorial pick
Z.ai (ChatGLM) wins our composite score (88/100). It edges ahead on aggregate — but the right tool depends on which dimensions matter most.
Related head-to-heads in AI chat.
Z.ai (ChatGLM) vs ChatGPT — AI chat
BigBang Scores 88/100 vs 91/100. Pricing, capabilities, and editorial verdict inside.
Z.ai (ChatGLM) vs Google Gemini — AI chat
BigBang Scores 88/100 vs 90/100. Pricing, capabilities, and editorial verdict inside.
Z.ai (ChatGLM) vs DeepSeek — AI chat
BigBang Scores 88/100 vs 88/100. Pricing, capabilities, and editorial verdict inside.
Z.ai (ChatGLM) vs Pi - frequently asked.
Direct answers tuned for AI search engines (ChatGPT, Perplexity, Claude) and Google's People Also Ask.
The short answer.
Z.ai (ChatGLM) wins on aggregate, but Pi pulls ahead on specific axes - the spec sheet above shows where each one earns its keep.