Claude Code $20 vs Codex vs Gemini CLI vs GLM-5.2: Which Coding Agent Plan Is Best in 2026?

The 2026 coding agent market has four viable subscriptions, and the answer to "which one should I use?" depends entirely on how you code, how much you code, and which models you need.

Each of the four major options — Claude Pro ($20), ChatGPT Plus with Codex ($20), Google Antigravity (free–$200), and Z.ai's GLM Coding Plan ($18–$160) — has different model quality, usage quotas, peak-hour multipliers, and tool compatibility. The decision matrix has gotten genuinely complex.

This guide compares them across the dimensions that actually matter for daily coding work: model quality, usage quotas, hidden costs, and which agent harness each one works with.

The Quick Matrix

Claude Pro ($20): The Best Deal in AI Coding

Anthropic's $20 Pro plan includes Claude Code, Claude Cowork, and Claude Design — three products that competitors charge separately for or do not offer at all.

What you get:

• Claude Code CLI and IDE extension included
• Access to Sonnet 4.6 and Opus 4.8
• 5x the usage of the free tier
• 5-hour session windows with weekly caps
• Projects, Research mode, connectors, memory

The catch: Usage limits are real but opaque. A heavy coding session can exhaust the 5-hour quota in under an hour with Opus 4.8, especially on large codebases with long context. The $100/mo Max 5x plan exists for this reason — it gives 5x the per-session usage.

Best for: Developers who want the best model quality at a flat $20, and who do not regularly hit the usage caps. If you fit that profile, nothing beats Claude Pro on quality-per-dollar.

ChatGPT Plus ($20): Codex Included

OpenAI folded Codex into all ChatGPT subscription tiers in 2026. The $20 Plus plan gives you Codex in the CLI, SDK, and IDE extension, backed by GPT-5.5, GPT-5.4, GPT-5.4-mini, and GPT-5.3-Codex.

What you get:

• Codex CLI, SDK extension, and IDE extension
• Model selection from GPT-5.5 down to GPT-5.4-mini
• Per-5h message quotas that vary by model (GPT-5.5 gives ~15-80, GPT-5.4-mini gives ~60-350)
• Additional credits purchasable when limits are hit
• Business tier at $20/user/month with central billing

The catch: The per-5h limits on GPT-5.5 are tighter than Claude Pro's equivalent. The GPT-5.4-mini model gives more quota but lower quality. Codex does not include the cloud task features (GitHub code review, Slack) on the Plus tier — those require Pro 5x or higher.

Best for: Developers already in the ChatGPT ecosystem who want Codex access without a separate subscription. The GPT-5.4-mini model is adequate for routine coding and stretches the quota further.

Google Antigravity (Free–$200): The Newest Player

Antigravity (which absorbed Gemini CLI in June 2026) takes a different approach: a free tier, then Pro at $20, and two Ultra tiers at $100 and $200 that scale linearly in quota.

What you get:

• Free tier: Gemini 3.5 Flash, Gemini 3.1 Pro, Claude Sonnet & Opus 4.6, unlimited tab completions and command requests
• Pro ($20): More generous rate limits, flexible AI credit pool
• Ultra $100: 5x the Pro rate limit
• Ultra $200: 20x the Pro rate limit
• Rate limits now pooled across models — cheaper models effectively give more total quota

The catch: Antigravity is new and still maturing. The migration from Gemini CLI happened on June 18, 2026 — workflows that relied on the old CLI need to adapt. Model quality is competitive but Gemini models still trail Sonnet and Opus on complex code generation tasks.

Best for: Developers who want a free entry point with real capability, or Google Cloud customers who can integrate Antigravity with their existing infrastructure. The free tier is genuinely usable for light coding.

GLM Coding Plan ($18–$160): The Volume Play

Z.ai's GLM Coding Plan targets developers who need high volume at low cost. GLM-5.2 scores within reach of Fable 5 on planning benchmarks and costs roughly a tenth as much per token.

What you get:

• Access to GLM-5.2, GLM-5-Turbo, and GLM-4.7
• Per-5h prompt quotas: Lite ~80, Pro ~400, Max ~1,600
• Compatible with Claude Code, Cline, OpenCode, and Cursor via OpenAI-compatible endpoint
• Open weights (MIT license) — deployable on your own infrastructure
• Cached input discount at ~$0.26/MTok

The catch: The multiplier system is confusing. Peak hours (14:00–18:00 UTC+8) consume 3x the quota for GLM-5.2. Off-peak is 2x normally, but a promotion through September 2026 drops it to 1x. The Pro tier at $72/mo ($50.40 yearly) is the sweet spot, but that is significantly more than Claude Pro at $20. Lite at $18/mo is comparably priced but gives only ~80 prompts per 5 hours.

The pricing breakdown by billing cycle:

Best for: Developers who need high token volume, work in UTC-off-peak hours (US/European time zones), and want the flexibility of open weights. If you are hitting Claude Pro limits weekly, GLM's Coding Plan becomes cost-effective.

Cost Comparison: What You Actually Pay Per Session

The flat subscription price tells only part of the story. The real cost depends on how the quotas work and whether you hit them.

The GLM-5.2 API at $1.40/$4.40 per MTok is the cheapest per-token option on this chart, but it has no flat-rate ceiling — the more you use, the more you pay. For light to moderate use, the $20 flat plans are cheaper. For heavy use, the GLM API or Coding Plan becomes cheaper than upgrading to $100+ tiers.

Model Quality: The Real Differentiator

Cost does not matter if the model cannot do the job. Here is how the model tiers compare for coding tasks:

Claude Opus 4.8 remains the strongest individual model for complex coding work. But GLM-5.2 closes the gap on planning and implementation at a fraction of the cost — recent benchmarks show GLM-5.2 scoring 9.0 vs Fable 5's 9.1 on Kilo Code's planning task, with GLM costing roughly 1/10th.

Which Agent Harness Works With Which Plan

Not every plan works with every agent tool. Here is the compatibility matrix:

Claude Code is the only tool that is truly "native" to Claude Pro — the others require API key configuration. GLM-5.2 supports an OpenAI-compatible endpoint, which means it works with virtually any agent harness that supports OpenAI models.

Recommendations by Developer Profile

Casual coder (a few sessions/week)

Claude Pro ($20) or ChatGPT Plus ($20). Either flat rate covers your usage. Pick based on which model you prefer for occasional work.

Daily driver, moderate usage

Claude Pro ($20). Best model quality at the price. If you hit limits, supplement with GLM-5.2 API ($5-15/mo extra) for high-volume tasks like boilerplate generation and CRUD work.

Heavy daily coding, hitting $20 limits

Tier 1: Keep Claude Pro ($20) as primary. Use for architecture, debugging, and complex tasks. Then add GLM-5.2 API or Coding Plan Lite ($18). Route routine implementation and agent loops to GLM. Total: ~$38/mo. This is the best quality-per-dollar combination.

All-day agent loops, autonomous coding

GLM Coding Plan Pro ($72) or Max ($160). The flat-rate subscriptions make sense when you are running agent sessions that consume hundreds of prompts per day. Alternatively, GLM-5.2 pay-as-you-go API if your usage is spiky.

Cost-sensitive, needs volume

GLM-5.2 API ($1.40/$4.40 per MTok). No flat rate, but the lowest per-token cost. A heavy coding day might cost $3-5, which beats any $100+ plan if you have off days.

Wants open weights, self-hosting

GLM-5.2 (MIT license). The only option here that can run on your own infrastructure. The 744B MoE model requires serious hardware, but quantized community variants are emerging.

The Bottom Line

For most individual developers not hitting usage limits, Claude Pro at $20/month is the best value in AI coding right now. It has the strongest models, the most polished agent tooling, and a flat rate that includes Code, Cowork, and Design.

If you are hitting limits, supplementing with GLM-5.2 — either via the Coding Plan or pay-as-you-go API — is cheaper than upgrading to $100+ plans. Use Claude for the hard thinking, GLM for the volume.

If you want a free starting point, Antigravity's free tier is genuinely usable, and the $20 Pro tier is comparable to Claude Pro with different models.

If you are already in the OpenAI ecosystem, ChatGPT Plus with Codex is a fine choice, but the GPT-5.5 quota is tighter than Claude Pro's equivalent, and the GPT-5.4-mini model is a noticeable step down in quality.

Related Reading

• GLM-5.2 vs Claude Fable 5: Kilo Code's Planning Benchmark
• GLM-5.2 Beats Fable 5 on Reasoning — 24 Hours After the U.S. Export Ban
• How to Run GLM 5.2 in Claude Code, Pi, OpenCode & Every Harness
• Claude Code Pricing Guide 2026
• OpenCode: Open-Source AI Coding Agent Guide

Pricing and plan details accurate as of June 19, 2026. GLM Coding Plan off-peak multiplier promotion valid through September 2026. Claude Pro annual pricing at $17/month. Google Antigravity pricing as announced at Google I/O 2026. OpenAI Codex pricing as published on developers.openai.com/codex/pricing.